Struggling to Lose Weight - Advice Needed

I wanted to post and see if anyone's had the same experience as me. Basically I've been struggling to lose weight and I thought about how it started. I used to be really thin and have a fast metabolism I was like 115 pounds a couple years ago, and losing weight unintentionally too, but a couple years ago I went on birth control and gained 30 pounds with no change in my diet. I was experiencing really bad side effects as well so I went off of it but the weight gain continued and I gained even more weight and now I'm at 149 pounds and super unhappy with myself. I only eat 1200 calories per day (I'm short so that's what's recommended for me for weight loss) and I get a lot of activity at my job, but it still keeps slowly creeping up and not going down at all. I don't know how to fix it so I wanted advice. I haven't wanted to talk to my doctor about it because my old doctor used to say I'm just being paranoid, don't need to lose weight, or accused me of having an eating disorder. I really would like to lose weight before it gets any worse since I am in the overweight category for my height now and I've noticed it being worse on my joints and my back.