Am I on my way to an eating disorder?

I'm 16, 5'9", 130 lbs. I think I'm fat although according to BMI calculators I'm on the verge of being underweight. I go running 2/3 times a week. I constantly think about how my body looks, and I'm very negative about it. I used to eat lots of food but for the past two weeks or so I've been eating ~1000 calories a day and keeping track of what I eat.

I have little self-control; when I'm hungry, I can't force myself not to eat. It's just that I for some reason haven't been hungry and have to force myself to eat sometimes, and afterward I feel guilty about it.

I'm not sure if it's serious or not because no one really notices; my parents seem oblivious and my friends don't really seem to notice either. In fact, one of my friends always tells me I need to cut down on the amount of food I eat and/or diet.

Am I okay? Please help :(