How can I make sure my weight consciousness doesn't turn into an eating disorder?

I’m 16 and I’m really conscious of my weight. I want to be slim because at the moment i’m no where near. I try to lose the weight but I cave and eat again. Then I feel even worse and annoyed at myself for it. I don’t like to weigh myself because I get upset, but I know no matter how thin I am i’ll always want to be thinner. I’m worried what this means. I’ve spoken to my friend about it but I dont think he really understands. He tried to help me through it about a month ago, but I can’t talk to him now because he said that if I didn’t stop it he’d tell someone. So I pretended I was fine. I don’t want to put this on him again. It’s not fair. What do I do? I cant talk to a parent or anything like that. I dont have a full on disorder but I’m worried it’s going to turn into one.