Whats wrong with my sister?:(?

tell your mom ... maybe she will talk to your mom :) , and maybe the eating disorder is coming back . she may need to go back to the doctor.

She might have bulemia, or she might just be a teenager with insane horomone fluctuations. Give her some space and when she has calmed down, try to have a serious conversation with her, and try not to be judgemental. Also, I had my period 3 times while pregnant. If there is any question she should see a dr. Don't let thm put her on meds because she is emotional. It's normal, it will pass. She just needs to know she is loved and supported right now, because nothing probably makes sense to her. Maybe outline the things she should be focusing on right now. Like getting good grades so she can go to college, and to focus on that. Nothing else really matters at this point for a 16 year old. She shouldn't be having sex, but it's good she is on the pill and that you know. Maybe make an appointment for her to see a counselor, maybe she just needs someone to talk to that won't take sides or judge her. Help her gain perspective. If she is depressed, she probably has no appetite, it may not be an eating disorder. But if she does, she is not going to admit it, and no matter how much weight she loses, it's still (5 more lbs, etc) but it is a disease, and she won't be able to stop. Some people learn to eat in front of family, then they just go purge immediately, or as soon as they can. Just don't push her. kids do crazy things. Good luck.