Anorexia?

I'm 1.73m and 54kg. I don't think I'm fat at all. But everytime I'm sad or nervous or anxious I throw up. I lose appettite, can't eat anything and if I do, I throw up. If I'm depressed I lose lots of weight very very fast. I've been told that this is called "real anorexia", as opposed to "anorexia nervosa". Is that true? Is it an eating disorder at all?