1200 is too little. That's 10 cals/lb. That's a cutting diet for exremely rapid fat loss.
You've got to start eating more and that's all there is to it. I know, I know, "if I eat more I'll gain weight"...
BS, I've heard it all before. If you don't eat enough, your metabolism slows to nothing and all you are able to do is store everything you take in as fat.
Everyone who wants to starve themselves that I've managed to convince to eat enough finally started building some muscle, burning off some fat, and looking good.
Post up some pics. I'll bet you are all soft looking at that small weight. Why? Because you don't eat enough to have any muscle.
Sorry, not trying to be harsh, but starvation is NOT a way to good health...it can only do bad things for you.
BTW, I once weighed 300lbs on less than 1000 calories/day so I know what I'm talking about. The pic to the left of this post is me this past October. I'm nothing special to look at, but my 4000-5000 calorie a day body is much better than my sub 1000 calorie/day body.
Throw away the scale, get the
tape measure, find your
body fat percentage, get some food in you, get in the gym and build some muscle...then you'll be fine. Don't worry about weight...the BMI and "healthy weight for height" is a terrible, harmful way to go...it will simply lead to bad health.