can someone help me?

i have never done this before. i guess i just need someone to talk to, so here it goes. recently, i have been very concerned with my weight. i have never been 'fat'. i have always centered around 150 lbs at 5'10. a few months ago, i just got tired of my curvy look and wanted something more 'catwalk'. i started taking diet pills and lost about 20 lbs. my friends, family, and boyfriend all say i look too skinny, which only fuels my desire to lose more weight. i am now at 130 lbs, off the diet pills, but i have started experimenting with bullimia in order to maintain my weight. i hardly eat as it is, but i feel the need to try and throw up small meals a few times a week. i guess the breaking point was when i was babysitting a little girl the other day. she has autism and she only eats starches, so i made us macaroni. after a small bowl, i went into the bathroom and began purging. the little girl walked in and stood next two me near the toilet with her finger down her throat, imitating me. i tried to push her out, but she remained there, and i was too determined to barf up the pasta that i didn't kick her out.
i don't know what to do. in my mind, i have this fear of food. i know bullimia is bad and wrong, but i know that i would gain my wait back without it. plus, it helps me to binge and not feel guilty. i am just afraid that its interferring too much in my social life (i'll do it at parties, at bars, at my boyfriends house, etc). someone talk some kind of sense into me, please.