Hello JonT -
It sounds like you have a good support network, and the desire to change, which are two of the most important pieces to overcoming depression. hopefulmigrainer and levon have it right. Don't let this go on too long. It can be hard to suck it up and say "I can't do this alone", but it sounds like you are ready to get some help, and it is better sooner than later. Talk with your parents or not, but definitely seek out some professional help. Regardless of how you feel, you aren't alone in this, and there is hope.
I wish I had some words of wisdom about fitting in, but I don't think I've fit in since I was a teenager. I've moved around so much in my life that I'm one of those people who just drift away. I do know that when I make friends now, they are definitely genuine friends. I don't have a large circle of friends, but when someone is let into my circle, it is because they are person who accepts me. I used to think that no one could accept poor old depressed me, but I've been proven wrong several times.
Good luck, and know that there are people who understand what you are feeling.
Diagnosed UC July '06
Asacol, prednisone, welbutrin xl, florastor