How to fix a slow metabolism? Please read?

I've been on a 800/900 calorie diet for 1 year and a half now, I've lost 66 lbs altogether, I'm currently 175, my bmr is 1550, however I'm no longer losing weight. What should I do? I'm literally terrified by the idea of increasing my calorie intake despite people telling me that I should eat at least 1200 calories. I got to a point where I can't eat anything that exceeds my daily 900 calorie intake otherwise I gain weight. I weighed myself on Monday and I was 175, this morning I had only lost 0.2 lbs. I'm so stressed, I'm constipated all the time, I can't sleep and I also have anxiety issues. Can anyone help? Any avidce is sincerely appreciated. I can't take this anymore, I refuse to eat more because I'm convinced that I will gain weight, I know I've ruined my body and my mind by restricting my calories, I'm just desperate though so please help.
How to fix a slow metabolism? Please read?
Add Opinion