Depression + Social anxiety. Coping is pretty damned hard, I mean life with a mental illness is stressful enough as it is but yeah, pretty much everything that's being mentioned. Don't isolate yourself if you can, as much as you may want to -unless people are being assholes or you need quiet then okay because when you're alone, though it may feel nice and stuff, you're left alone with your thoughts and those thoughts can be pretty dangerous. Especially with depression.
Laughing is always good. For me, I don't like being around people and don't really have 'friends' so to speak but I have the internet which makes me pretty content. I know I have to get out more but my social anxiety is pretty extreme. Do things that make you happy. Food isn't a really good option if you're depressed for the long term. If you've just had a really stressful day or something then sure but not like, every day all the time. The risk of binge eating all the junk food is too high and then the guilt hits you afterwards and you feel worse.
I like to watch shows. And read. Escaping in a good book can do wonders. I usually read a couple of chapters before bed or after school if it was a crappy day or sometimes during lunch or something- actually whenever I feel things are pretty damn crap and I want to go away. I have a bunch of movies/ anime/ shows that I keep waiting for a rough day or something and that's always something to look forward to if you're in school and you just want it to end.
Of course, if your depression or mental illness is making it hard to live life as you want it, you should really go and seek help as the others have said. And I agree with whoever said to keep seeking help even if the first or second one is crappy, especially school counsellors. Mine only lasted a few sessions and did nothing. Talk to someone about it, vent. I'll be here if anyone needs to talk about anything.