Hi. Im only 16 years old. 5'4 and i weigh 145 lbs. I'm not overweight. Nor am i pregnant. I started having my period at age 12 && they were pretty normal for that age. But starting about 2 years ago, they became extremely abnormal. I have had only 2 periods since January of this year and they are very light, at that. I have no idea what is causing this. My mom took me to the doctor today, and they ran blood work. I am extremely scared and don't have any idea on what to expect. Yes, i have been sexualy active but not in a long time. what can be causing my periods to be so abnormal at such a young age?? i understand that young girls periods are rarely regular, but mine were at one point, and then stopped. what could it be?