I keep losing weight

I'm 13 and 5'1 1/2 and I weigh about 82 pounds. At the beginning of this year I weighed 95. I felt fat so I stated a diet. Just eating a little less. I said I would stop at 92 pounds, than 87, but now I'm fine with my weight, but I keep losing it! I've been trying to follow a meal plan given to me by my dietitian to get up to about 1300-1500 calories a day, which was a huge stretch from my usual 800, but sometimes I still can't get up to 1000. Whenever I do eat over 1000 calories, I stress out and feel fat, even though I know I really need more. My dietitian said I need to get to 2,200 calories a day because I dance 4 times a week, but that is so much! My mom is threatening to send me to an eating disorder center somewhere out of state, and I'm really scared, I don't want to leave my wonderful life and family, and I don't want them to have to spend a huge amount of money for me to get better. I know I need to eat more, but I'm afraid I will get fat and be made fun of, and since I'm a dancer, I feel pressured to stay skinny. I really want to prove to my mom that I can get through this, but how? Every time I eat a little more, like mini meals 6 times a day, but a little more calories, I loose weight! I don't know what to do and I can't even sleep anymore because of this. I just want to enjoy my life and be a normal kid, and I hate wasting my childhood thinking and worrying about eating, because I know how precious childhood is and it should not be wasted, but I can't get food and calories out of my head. Can someone please help me so I don't have to go to a center?
P.S. I am currently talking to a therapist.