be skinny

i wish i were skinny! its not fair! i seen wat food does to people and its not nice. all these people around me all natrully skinny showing of thier bodys and im to scared to wear a swimming costume! im 9 stone and not exactly obese but i feel it! all these people just found out i was bulimic and iv had ramdom people cumin up to me in scool telling me im skinny and slim and y do i do it to myself. does any one have any more ideas on how to be slim. iv diet constantly but it dnt work for me.