If my period is more then a couple of days late, I get cramps, before I got onto a medication for PCOS, I could go a month or two missing my period, and then it would be sooo painful. I would also get cramps for days. I was put on Spironolactone aka Aldactone. It blocks the Androgen as far as I know. If I miss a couple of days, then my period starts later. If you are under 30, don't smoke and lead a fairly healthy life style, going on the pill is another option. It's not one for me, I'm too old and I smoke lol.
I was told that there was slim to no chance of getting pregnant, though I tried hard up to 30 to get pregnant. It's common for the uterus to get "tipped" and you may not being able to gestate, which basically means, you could get pregnant, but it won't hold.
It's really important that you get your period regularly, you need to shed your endometrial lining, for some serious reasons.
I would seriously go see a GYN and get a referral to an ENDO, they both can help you with options. I know there are more options out there.
Have you been diagnosed with PCOS? If not then you should ask your doctor to check. It is normal to go months without a period with PCOS because instead of being released, the egg is being trapped in a cyst on the ovary. Even though it is normal, it is not good for the uterus to not shed every month or at least four times a year. Last year, I had two periods, with a 7 month break in between.