Petite frame, hypothyroidism and motivation

I am sick of being overweight! I am on the high side of normal for my BMI, only 10-15 pounds away from my goal weight but I can't stop overeating and drinking. It doesn't take much, with my small frame and hypothyroidism my TDEE is 1500, and eating 1200 calories a day (or less) is nearly impossible. Every time I am on track I have too much food or drink, and before I know it the pounds pack back on.