You ever feel as though there's absolutely no hope for you? Maybe it's just a mood swing, but I seriously feel fucking hopeless right now.
I've mentioned this before, but I feel I should reiterate: When I was your age*, I felt like this every day, had screaming fits in my car during my commute to/from work, and cried myself to sleep every night. I had been somewhat depressed since age 13 and it really started hitting at age 24 when I discovered how underpaid I was. I was the poster child for that ForeverAlone pic, too. My life started very slowly turning around at 27 or 28, and it has very** gradually become amazing.
The best thing to really do is to separate (A) the things you have little control over and (B) the things you have control over; then use the items from the B column to gradually improve yourself in any measurable way you can. At that terrible point, I basically had two friends whom I didn't really like hanging out with. I had some money from my job, so I reconnected with college people an hour away who had a sort of communal house, and I just visited them weekly. They were an hour away, but it was really the only way I could get any sort of real social exercise. I also tried volunteering to help people (there was, for instance, a local organization that was getting together people to revitalize public schools), which gave me something to do that wasn't utter routine and also made me feel a little better about myself. The other thing I had control over was my own body. I took initially extreme measures and then a lighter touch to reduce my weight by 70lbs (~30kg) and get in better shape. Not eating takes no effort, just a little bit of masochism. Walking around, which is how I started exercise, is pretty easy if you're able to play games or read e-books while walking (my peripheral vision is pretty good, though I did hit my head into an errant tree branch every coupla weeks.
Anyway, if you focus on the things that you can conceivably change, and if you keep at it rather aggressively, you'll eventually find that things can improve over time. You just have to play the Long Game.
* lololol, I'm at the stage of life when I tell people "When I was your age..."
**
Very: first drink at 30, first girlfriend at 30, first sexing at 31, first decent job (the current one) at 32; now I'm 36 and people think I'm some sort of social mastermind who's well off and gets laid all the time with a variety of models. I silently perpetuate these myths, and they're not without basis, but I'm just glad that people don't think I'm some sort of terrible person.