What Is Wrong With Me? long decription but please read?

A few months ago i started feeling really sad and i didnt know why. Everything tasted bad and i had no appetite so i didnt eat for a few days. I talked to my boyfriend about all this and he said i should eat. Then i started feeling like i was fat so i continued to not eat and then i started eating around 500 calories a day. Then my bf broke up with me becuz of it so i started eating normal again and we got back together . I was still very sad and didnt know y. My parents r getting divorced and my mom thinks i have anxiety. Lately i have been feeling better but just the smallest things upset me. My mom acts like such a b*tch a lot and im so sick of it. I used to cut myself and i occasionally still do. Im over sensitive to everything and i hate it. I dont want to talk to my parents or counselor. Ive been starting to feel upset again lately. My boyfriend and i have been arguing a lot for the past couple months. Sometimes becuz i want to diet becuz i feel like im fat. Im 12, 5'2, and 100 pounds. Ive been eating 1300 calories a day and i was 102 but i lost 2 pounds. I think my stomach sticks out too much and is flabby. Other times i dont even know why we argue. I love him. I really do but a lot of times HE is one of the reasons i get upset now becuz we're always arguing. I really think im just over sensitive but i dont know how to stop. I count the calories in everything. Everything. Sometimes i feel like i nvr want to talk again but i do. It feels good to hold my breath for a while. My throat and head start pounding and it feels good but then of course i have to breathe. I cry a lot, almost every night. My stomach always has this nervous feelling in it and my arms shake a lot. I feel like i have to keep doing things with my hands so at school i carry a small mirrow every where i go to be holding onto something. I always look in it to make sure i look ok. What do i do? Whats wrong with me? :'(