I wrote this on another thread about depression... It's a common problem, and most of it applies although I have no idea how old you are. It should give you some ideas the think about.
You've already identified the behaviours, not eating, avoiding friends, etc. Although you don't feel like it, if you're aware of it you can change it. Eat when you don't feel like eating. See people, and here's a good tip, spend the entire time with them listening to them. Don't talk to them about being depressed, or anything, just really try to listen to what they're talking about and engage with them. It's surprising what this can do when you're stuck in your own head.
Also nervous breakdown is a bit outdated, and no, you're not having one. You're depressed (depressed literally refers to the decreased emotional response to things. You feel flat and don't enjoy things you normally would). A nervous breakdown was used more for anxiety attacks and people ceasing to function. Function meaning your ability to get up, feed yourself, go about your business. Can't remember if I mention below but get counselling, call a help-line. It may seem like a big hurdle to get the courage to do it but set your mind to doing it and before you know it you'll be having a great chat with some complete stranger and feeling a 1000 times better.
-------------my previous email----------------------
First of all. Take it easy on yourself. You're 15 and being 15 does suck, at least for most of us. If you're life is fantastic at 15 you're probably going to be one of the dullest adults ever so realise that at least it's not a great time for most people.
You are basically in metaphorical prison at the moment. It sounds terrible but it's not that bad. Because you're 15 you legally not allowed to do a lot, you don't get to make a lot of choices about what you do. You have to go to school. You have to get along with the random friends you make at school. You have to follow your folks rules. You are restricted, like being in a prison. This helps contribute to the "triangle of depression", which are these 3 beliefs 1. I suck (internal), 2. The world sucks (external), 3. Both the world and I are going to go on sucking (ongoing). You need all 3 to be really depressed. We'll get into breaking those down a bit later...
First of all Suicide ideation is very, very common at your age, and really it's ok. Fantasising is a healthy way of figuring out how you feel about anything. But with suicide there's a line you need to be aware of. Fantasising about what it would be like if you were gone is fine, as long as you're not fantasising about the exact details of how you'd do it. For example, wondering what people you know would think or do if you were gone is fine, even healthy. Imagining where you'd buy the rope, the steps necessary, people's timetables so you'd know who would find you... that's bad. If you've got to that point where you're actually making realistic plans then SPEAK TO SOMEONE. If you don't feel comfortable talking to school counsellors, friends, family etc then call one of those anonymous help lines. That's what they're their for and they'll perk you up straight away. The reason people contemplate suicide is because they feel there isn't another "out" from their current situation. Remember there is always another out. Always.
So let's break down the triangle. You've been depressed before and then felt better. Doesn't matter how bad you've felt before, strangely you always get over it and have a laugh at some point. Plus things never stay the same, good or bad, but especially the bad. Point 3. Ongoing suckiness rarely exists. Maybe for people in horrible marriages, or with chronic illness, but NOT 15 year olds. Your situation will change whether you want it to or not. You're entire life will go through transition after transition year after year for a good while yet. Some good, some bad. The bottom line is that things will not go on sucking indefinitely.
Point 2. Maybe the world sucks around you right now but that will change. Also as much as it may suck it's not war torn Africa, or the slums of mexico city. This isn't a lesson in well-you-shouldn't-ever-feel-bad-because-you're-not-starving. Just take a step back and realise that although you may not like where you are you're in a better position to make your life better than others. You're in a more hopeful situation. The environment around you has a much bigger impact on how you feel and behave than most people realise. Scientifically proven in fact. Plus, pretty soon you'll have more choice about your environment. If you go to college you get to pick what you study, who you hang out with, where you go to socialise. You go from prison to half-way house as it were. You get more choice.
You can also change what's going on right now. You are not responsible for your friends' behaviour. If they want to be jerks, that's fine. You can either smile and say nothing, have it out with them, or just change where and when you see them. Whereas people will gladly see things as their fault and not a result of their environement, strangely they don't see themselves as an agent in other people's lives. What you do affects your friends. And you ARE responsible for what you do. As I said, you're in prison, maybe you need to keep your mouth shut and that's hard, but don't think that's the way it's always going to be. Most people will tell you they are no longer friends with people they knew in High School. Maybe one person. Think about that. Millions of people go through high school and most don't stay friends, and that's because you don't have much of a choice right now.
Point 1. This is the tough one. How do you get confidence, how do you convince yourself you don't suck. This might sound a little cruel but take it in a humourous way. Suck it up, Boo hoo to your self-pity. Self-pity serves no good purpose generally. If you sit there thinking about why it's all so unfair, and how the world isn't fair on you then all I can say is I can't help you. The world isn't fair, not by a long shot. It never will be. The only justice you will ever see is the justice humans implement in society. I am also an atheist. If there is a god he certainly doesn't seem to mind children being painfully murdered or killed. He also allows extremely rich and evil people to destroy the lives of others at a whim. There's no justice here. So again, count yourself lucky you were born an American and probably not in povery, rather than an Estonian girl whose best career option is sex trafficking.
So whenever you catch yourself feeling self-pity there are two things you can do 1) See it as an indulgence, like eating a lot of chocolate. As long as you're aware you're doing it it becomes more funny and you get less bitter about the whole thing. 2) Once you admit it move on. Come up with a plan to fix whatever you're moaning about and do it. You don't have to be happy about it, or get yourself psyched like some Anthony Robbins oprah-bot. Just face it like a chore, like mowing the lawn. It's just something you've got to do. An example. You've got to do something you hate/fear, like public speaking. Just accept that you have to do it, then do it. 90% of all phobias are caused by people just refusing to confront their fear in the first place. And self-pity springs from fear. Every time you hear someone whine about how unfair something is for them you can usually see that if that person plucked up a bit of courage then they'd have done something about it.
But I did say, take it easy on yourself. That's not self-pity. Realising that you're fine the way you are is are hard thing to get sometimes. I didn't really get it until I was 30, and only when I let go of other people's expectations. And let's be clear here, we feel a lot of expectation on us. Not just the obvious body image, career-minded, money focused, achievement grabbing, glory hunting image the media suggests we should all be. And not just the good boy, work hard, study for the future image our parents want. The expectations you've got to watch are the ones you make in your head about how you should behave and act around your friends and around girls.
For example, if I want a girl to like me I should.... get better clothes, be more funny, not talk about stupid stuff I read on the internet... and so on. It's tough because a lot of the time those goals are what really motivates people to do stuff, like go out and socialise. Problem is you'll find the expectations are never clear cut. You'll meet a girl and she'll say "I love guys who are career minded and have a 5 year plan". And next week she'll start dating the lead singer in a crappy metal band.?? And you're lucky if you even get that clear a signal from someone about what they want. Lots of people behave the way they do because they THINK that's what people expect them to do. But here's the kicker, it's an expectation they created themselves. I knew a couple where the guy tried to be this super boyfriend all the time because that's what he thought she expected. It wasn't, but nothing she did or said changed his belief. Of course no one can be super boyfriend for ever so everytime he failed he assumed she hated him for it. Then he'd resent her for hating him because after all he was trying to be super boyfriend. All of this was in his head though. She didn't think he'd failed, she just liked him the way he was but clearly he didn't.
(for some interesting reading on this look up Carl Rogers - in particular "conditional love" leading to "incongruity")
So all that leads to the phrase "just be yourself". Which just sounds stupid without clarification. It's like people saying "Just relax". Both are good advice but you'll have to figure out the tools to just being yourself. And the best way is practice. Experience as much life as you can. The main difference between a 16 year old and a 36 year old is experience. You won't know what you want, or what to do without at least trying stuff. Change jobs, move around, go travelling, read a lot. All that stuff will help you figure out what is true and what isn't.
So here's the last crucial bit of advice I can give. People haven't got a f***ing clue. That includes you and me and everybody else. Despite all the religions, all the philosphers, all the scientists, all the world leaders, no one can definitively say they've got THE answer. If they do then they're a con man and trying to sell you something (see Anthony Robbins). Usually there's something to learn from all these places so listen, analyse, figure it out, just don't accept it at face value, and don't feel bad because you disagree. I've studied psychology, philosophy, medicince, law, and have done a fair amount of reading. I've travelled and met lots of people. My over riding theory on people is this. They do whatever the hell they want and then rationalise (justify) it afterwards. If they succeed they'll tell you they knew they were right all along. If they fail they'll come up with an explanation for their failure. Generally the true reason for the behaviour is a mystery to them. It's like showing children a magic trick and them asking them how it was done. They'll tell you something but who knows if it's true.
And that's fine. There's not a lot wrong with people doing that. That's what they do. The lesson to learn from this is that you should listen to yourself first. If you decide to do something and tell people, believe me, they'll all have an opinion, and they'll all tell you what they think you should do. That's fine, listen to them, but remember most of them are talking out their asses. Most of them will say the first thing that comes in to their heads without doing any research or analytical thinking. That's because there's no risk to them, to them you're just an experiment. He was going to do this, I said this, then he did that... and they await the outcome. Don't let what other people say spook you. Trust you're own judgement. I literally got lost at sea once because I ignored my own judgement and let someone else decide (it was only for 30 minutes but I was kicking myself because I should have known better). That way your mistakes are your own, and so are you successes.
Anyway, not sure if that helps much. It's all the helpful stuff I've accumulated since I was your age and wished I'd known then.