What can I do about my weight?

I live in a flat, I'm 12 and 5ft2" more or less.I just don't feel right about myself, I don't want to be like my friends, all skinny and pretty, but I want to be myself, happy about my weight. As part of my regime, I eat healthy and instead of getting lifts, I take the bus with my friends in the morning and after school. When I get home, I feel different, I feel bad about myself, but I feel worse when I'm around my friends, I try so hard to be like them, but I don't want to be. I gave up. But now I want to try and lose weight, I can't weigh myself because we don't have a working weighing scale, and I don't have the time and patience to go to the doctor's to weigh myself, its too embarrassing. Anyway, I don't and not allowed to go out after school when I get back home, and I also hate aerobics like jumping jacks etc. or stretching. SO im stuck, and I don't know what to do, I try and try and try, bt all that deceives me. So I'll be my own weighing scale and agree to what weight i'm happy with...