Am I considered Anorexic?

So lately my grandparents and the rest of my family are saying that I am getting really thin and getting weaker. They say it's because I hardly eat. I don't eat breakfast because it gives me stomach aches and makes me feel sick for the rest of the day :puke:. I don't eat lunch but I peace on things like apple slices or crackers throughout the day. And If I do have lunch I don't have much because my stomach hates me if I get full or overeat. (I have stomach problems that nobody can find after many tests and biopsies) I eat a full dinner because by then I'm hungry and I usually have most of it and I'll be fine. Then have a midnight snack (mostly crackers) because I'm a night owl. And with me not eating that much food, I have lost 6 lbs. in a week and about a little under a pound every week after that. But right now I'm staying the same weight. (116-118 lbs.)
So back to the story. One of my grandparents is deeply worried that I am damaging my body by not eating. It's not much of a weight problem which is how I associate Anorexia, but more of a I just have a hard stomach. They say that I am looking really skinny (I still have a little chub on me so I don't understand that) and my grandpa is wanting me to eat foods that will give me more strength and to help me gain weight that I don't need to gain, and to eat more.
I just have 2 simple questions. Does this somewhat classify me as an anorexic and is eating this amount of food a day healthy?

Thanks in advance,
Mr.Stress...or whatever my username will be in the future...