if it makes you feel that bad, try and exercise more, get onto a healthier diet.
but it doesn't seem to bad to me, i think as you said having very skinny friends makes you feel pretty rubbish, it does with me too and i'm a size 10 (just shows how vain my friends are).. but yeah, it used to bother me tons how they managed to stay so skinny and never put on weight where as i was battling to keep my weight steady so i didn't put it on quickly, because i had fluctuated between them, but now its true - people prefer more fuller figures, being skinny is almost, i dunno, not appreciated as much.. but then again it is.
just keep yerself healthy and be happy within yourself =]