Too obsessed with fat?

I didn't notice fat so much in elementary school but into middle and high school, it really started to bother me. I don't like fat. The first thing I notice about people is their skin and weight. Sometimes it's not so bad on people when they shape themselves certain ways, but it's a fine line between what is okay and what is too much. I have some friends who are overweight and I don't mind it as we've been friends for years, but I don't want them getting any fatter. I think it's funny when people I don't like get fat. I feel embarrassed when my parents talk about how fat they're getting or eat too much in front of me. I don't want my parents to get very fat. I don't want my little brothers and sisters to get fat and sometimes don't let them have certain snacks when I'm in charge. I tell one of my sisters that she will get fat if she doesn't stop eating so much. I don't want to marry somebody fat or have fat children. I'm afraid of getting fat. I hate the places that have fat on me. I feel guilty when I think I've eaten too much. Sometimes I go up and down the stairs at my house or ride my bike if I think I've eaten too much. I've tried to make myself throw up in the past but I can't do it, I'm afraid it will hurt or I will get puke on my hand and usually stop after a few meager gags. I've tried to stop eating but am afraid that I will get caught and end up with more fat than when I started. But I want to get rid of it. I want to look like models on TV and in magazines, movie stars; I want my thighs to not touch when I'm sitting. I like to stick my fist between my thighs so they don't touch. I want this so bad, but then I tell myself it doesn't mean anything. I can go on, too, until one of my professors does a presentation on anorexia, bulimia, and I don't want to die, of course; but I see how skinny they are and how skinny I could be if I tried hard enough, and I told myself, tomorrow is your nineteenth birthday. Tomorrow you can start. Now today is my birthday, and I went online last night and read tips, and I've started restricting myself. I live with my parents but work two jobs over the summer and think I can do this. I like the feeling of being hungry, because I've done this before and know I'm beating it. But I'm scared, too, of things going wrong. I'm scared of being caught, but even more scared that when it's time to stop I won't know it. I'm afraid of this becoming my life. What is wrong with me?