How Fitness Became My Life

Hi everybody I am 19 years old. Before the summer of 2012 I put on a lot more weight when I went to college. I guess you call it the "freshmen 15". However even before that I had problems with my weight especially during high school. I tried to go on many diets but for some reason I could never stick to it. During last summer I worked out every day for 3 months. With the same diet of 1 meal per day and an hour of working out each night. It would involve crunches, pushups, jogging in place. I would also go to my local gym and hit the elliptical, jump roping, and running the track. There were times during the summer where I went on trips and ate a lot since I was with other people. At the beginning of summer I was 130 lbs. Then at the end I weighed 118 lbs. At the begging of my 2nd year I ate two meals per day and worked out for an hour at the gym. I felt like my weight was still going up and down. Then in October I started doing 1 meal per day. I dropped a ton of weight going down to 100 lbs. Since people noticed at school about my weight dropping to low I had to start eating more again. It was hard to maintain the weight I wanted. I also wanted to get rid of lower belly fat. I didn't want to lose to much weight but to have that nice skinny body everybody craves for. I know what I did was unhealthy which was why during my big winter break I ate 3 meals a day. Now my weight is 90 lbs. I suffer from Seasonal Depression which goes from winter to spring. Basically my body shuts down and wants all the sleep it can get. I struggled with it through school and while I am home. Being home I workout for 30 minutes each night. My goal is to over come it. I want to lose my lower belly fat, raise my metabolism, start eating properly without worrying about weight gain, or my stomach going back to the way it was again. Over this winter break my basic workout consists of crunches, reverse crunches, jumping jacks, lifting free weights, and bicycle crunches. My big question is how do I lose this lower belly fat?