Why can't I stop thinking about food?

I'm 25 year old, 5'3, female. I've had weight issues my entire life. I started gaining weight when I was about 12 and it's been a battle ever since. I've had tests done and it's not a thyroid issue. I've tried everything to lose weight. It's gone up and down. At my heaviest, I was about 220 pounds. I've done Weight Watchers, Sugar Busters, Atkins, over the counter diet pills, prescription diet pills, I've even resorted to bulimia at various times. You name it, I've tried it. Nothing ever sticks. I lost about 20 pounds on Adipex but after just a month and a half my body acclimated to the pills and it was like taking a vitamin...no effect. I was still hungry and thinking about food. It was disappointing because I had such success at first and several of my friends have lost 50-60 pounds and look amazing now. I don't know why it didn't work for me! I'll start losing but I can never maintain. I eat all the time. I'm hungry all the time and even if I'm not hungry, food is on my mind and it won't stop until I satisfy the craving. It isn't small amounts either. I've eaten a jumbo size meal from a fast food restaurant when nobody was around then agreed to have dinner with friends shortly after. I love food and can't make it stop. I try to exercise to speed up my metabolism to maybe help but the more I exercise, the hungrier I am and it's difficult to fit in much exercise since I work full-time and attend school full-time. I wake up at 5 to get to work on time then go to bed around 11 after getting home and doing homework. I'm exhausted all the time but can't quit school or my job. My biggest problem is that I can't stop thinking about food. Even when I try to use distraction techniques (read, go for a walk, go to sleep) I have food on my mind the entire time and once I'm done with whatever I'm trying to do to be distracted...I'm still wanting to eat. I try to go to bed to avoid eating and I can't fall asleep because food is nagging at me. I stopped keeping snacks in the house to try to keep myself from munching but I'm not too lazy to cook or to order pizza/chinese/whatever will deliver. I'll even leave just to get something I want to eat. I'm beginning to think I'm doomed to have a fat gut forever. I hate my body. It makes me self-conscious and holds me back from doing pretty much anything because I'm afraid of being judged/stared at. I'm so terrified I'm gonna have to be fat forever and ultimately end up dying alone because nobody is ever interested in me and I feel like it's because of my body.