I'm like you - I eat simply for the sake of eating. I didn't know that was a disorder! I don't know bad it has to be to be classed as a disorder,though..
I don't know why I do it - simply eat for comfort, I think. I've been depressed on occasions and eat simply so that i can forget things. However, I don't put on weight (which isn't a good thing - I hate to think of the state my inner body is in!) so people don't know it. My GP even told me I was underweight!! This didn't help. It gave me a kind of "invincible" feeling that I can eat as much as I want and nothing would happen.
Only recently when I realised how bad my health was (when I went for a check-up) did I change my habits.
I don't know how bad your case is, but maybe you should just attempt to stop eating. I know it sounds stupid, but that's all I did and it actually worked! However, if your case is really serious maybe you should see a counsellor or something? Good luck