Is this Anorexia nervosa?

Yep do your BMR they have a website at about.com do the formula the first one is how many calories your body needs to function. Second is your activity level added to the BMR and third how many calories to cut out to loose or keep your weight. Yes thats anorexia you are eating way to little calories your body is going to eat at your muscles. When you start eating you will gain back double. I suggest you find your calorie intake and do it the right way. Asap!