Is it normal?

So fat in 2016, I have only gotten my period 4 times. Sometimes I feel lucky, sometimes I get worried. I'm not sexually active, so I don't worry about being pregnant. And I'm not on any birth control to say it's that that is messing up my cycle. I've had an a super tiny cyst on my ovary since 2009. I've gotten it checked 2 times and it's still there, it doesn't grow and it doesn't shrink. Obgyn said it was normal. I NEVER know when to expect my period because it's never constant. One month I get it in the 20s, 2 months later I get it at the beginning of the month. I've heard of polycystic ovarian syndrome and also endometriosis. If I have concerns having this, can I tell my doctor and they let me know?