birth control
"Was put on this because of PCOS, did exactly what it was supposed to do.  Got my period exactly every 28 days, no major side effects except for weight gain (part of which I blame for starting college at the same time).  Didn't gain weight at first, then I gained 10-15lbs, and overall I gained 35-40lbs.  It wasn't easy to lose the weight on this either, even with diet and regular exercise."