I need help?

im 17 i weigh 235 thats fat but im 5'8 i just look tall n big.....im startin to feel horrible. reality hit me when i seen myself in a picture me & my gurls took at school...they all looked nice..all around 5'4 and averaged sized girls. My gut look so fat in the pic it messed my whole day up. I'm one of those girls that like to dress up cute..ya kno...i like wet seals clothes, hollister...but now it has become all the stuff i cant wear...i tried exercising..but now im thinkin about not eating for 3 months (just water and very very small portions of reg. meals) maybe i would at least loose 5 pounds a week for 18 weeks & i'll be back to 145....Do you agree with my idea???