I need advice!!

So today I went to the obgyn. I'm 16 and haven't done any sexual things. Well I haven't had my period for about 3 months and my doctor prescribed me medroxyprogesterstrone to make me have a period. I took the pill for 3 days and had a period. It's a 10 days pill and then wait a week and have a period. Then I didn't have a period for to more months so I went again to the doctor and he made me get a ultrasound done. The lady didn't see anything but my bladder didn't have enough in it to move around to see my ovaries but the doctor said he would be able to see if it was a big (5 cm) cyst. Which I didn't. But he thinks I have PCOS (polycystic ovarian syndrome) but also thinks I could have diabetes. I took a blood test today to know for sure. But he said before my next period (February) I need to decide to either take birth control, metformin, or medroxyprogestrone every other month. When I get older I still want to have kids but I don't know which ones to get on? Any advice?