I need help.. im doing things and i think i might need help..?

I'm 15 now but when I was younger, started at about 5, I wasn't eating as much food as i should've been and i was skinny, people called me anorexic and i hated it, as i grew i started to become self concious of my body but since last year i've either eaten that day or not at all, but it is either everything or nothing; i hate it but i can't change it. Lately I've been trying to do things like make myself be sick and even cutting my wrists a bit.. i cry a lot at night and i just don't know why and i don't know what to do. I thought all my emotions were because i lost one of my bestfriends and my grampy 2 years ago and i was close to them my dad is in Afghan and my brother is in Cyprus, my other brother is going into the RAF soon and 2 years ago I also made contact with my sister. I don't know why I'm doing these things, people have started to notice I look very tired when i go to school and look depressed ... help please?