period

I'm 17 about to be 18 in the summer. I've only had my period three times. One a year, different month though. I've been to the doctor and they said my hormone levels were good, I had nothing to worry about. They gave me birth control pills, but I only had my period for that month I took it (second time I had my period) and after 3 months from that I had it again by ever since that, I only get brown discharge and it last like a normal period 4-7 days. What's wrong with me? Am I normal?