I burn a lot of calories and don't gain weight, so does it matter if I am iating too much?

It can. It is important to look at what your calories are coming from (i.e. Fat, carbohydrates, or protein). If you are eating a lot to match the calories that you burn, you are probably in a good balance, which could explain your weight stability. You may want to consult with an endocrinologist if you think that your metabolism is out of balance, however.