Its taking away my chances

I'm 17 years old. 5'7 and 250 lbs. I have this addiction that rules my life but there is no controlling it. I will never have the normal chances at life. I go to college in August and I know how miserable I will be to be soo fat and in college when everyone else will be skinny.I have been overweight since I was 8. I was taken from my original family and placed in the hospital for mal-nutrition and ever since then eating has been life or death for me. I have been through the foster care system and of course the many different homes have all had their impact but the biggest thing I notice is that I always ate more than should. I don't want to live in my body anymore I feel so trapped but My adoptive parents think all I need is a little will power, trust me I've tried. I starved myself for one summer after 9th grade and took boxing classes I lost 30lbs and was so proud but when I went shopping for clothes my mother made me buy a size bigger than what I had wore before the weight lose. She said of course I would gain the weight back. I have tried everything.. I was binging and purging for 2 years in middle school but that shamed me as much as eating so I stopped.. I am not receiving treatment and probably never will because it would upset my parents. I want weight surgery and hypnosis.. They say it works... Its my only hope. I'm in high school and I hate myself to the point that I don't leave my house. I can't live like this forever