Struggles with weight.

I am 30 years old and since I was in junior high, I have struggled with my weight. In college, I took advantage of the work out facilities at the school and was able to get my weight to about 150. When I got back from college, I kept it at 170 until I got married and then I gained weight. In the summer of '04, I went to LA weight loss and lost 35 lbs. I was so proud of myself. I then got pregnant with my twins and gained 40 lbs. Now after my second pregnancy, I managed to loss 35 lbs.
Since the fall, I really have not able to loss much more. I have seen a doctor that diagnosed me with PCOS and percribe a medication that was supposed to help me balance my hormones and help me loss some weight. Because of the PCOS, I have made may changes to my diet. I do not eat fast food, fattey foods and I watch every calorie and chlorestral. Two months ago, I purchased a treadmill and have been on at least the 150 minutes that my doctor perscribed a week and sometimes more. But with all the efforts, I still struggle with the weight loss.
I have watch those around me who had baby's around the time that I had Joshua, and they have all managed to lose their baby weight and more, and I have a neighbor who is physically fit and just had a baby that most likely will get back into shape really soon and most likely I still will struggle to get the weight off despite of my efforts.
I do not expect the "Biggest Loser" results that they manage to get every week. But would love to see 1-2 lbs a week come off.
My goal is to be about 125 lbs give or take. That would make that my goal is to lose about 55 lbs.
I know I can do it, and I would love any encouragement or compliments as I try to fight this struggle. Maybe in a few months a new me will emerge out of my body.