My periods are still irregular, and I am concerned.?

I began menstruating in the month of July before grade 7 (I am currently in 10th grade) and have had probably only have had around seven to nine periods in that span (I've only had one this year, so far). I am also much more underdeveloped physically when compared to my peers. I have listen to what I was taught in health class and so I've waited for three years for things to even out, and my periods are still very unpredictable.

I am at this point, concerned. I know that excess hair is a sign of too much testosterone, and I have some unwanted, darker hair around my lip--not quite like a guy's hair, but dark enough to be noticed by others, and on my stomach. Could I have too much testosterone? Could it be affecting my menstruation issues?