Weight Loss Block?

I'm 15 and I'm 5'3". I use to weigh 166 and then I began my diet plan and for about 6-9 months, Now, I'm down to 147.6. I'm still not satisfied though. I've been dieting on a 1200-1500 calories diet, along with running for 30 minutes every weekday followed with another workout that consists of: 100 push ups, 200 crunches, 60 side crunches, 80 sit ups, and a 1 minute plank/wall squat. As active as I sound, you must be thinking i'm losing weight. However, I've gained weight. I don't know what's going on and it' making frustrated. I diet well, drink plenty, and exercise. Why am I not burning fat?