Take a pregnancy test first. Don't panic before you know the facts. It might not be either, it could just be your body is readjusting to not having the hormones from the pill. It can take some women up to 6 months for their cycle to return to normal after taking the pill.
If you do have PCOS, then you need to accept that irregular periods is something thats likely to happen to you, and not panic every time you have a late or missed period, but perhaps have a few pregnancy tests on hand so you can double check.
Do you not think it might be worth asking for a referral to a gynecologist to find out for sure whether or not you do have polycystic ovaries?