I have PCOS and was diagnosed by blood tests and scans a couple of years ago. I came off the pill and only had 6 bleeds in 2 years. Since then I have managed to lose weight and the doctor put me on Metformin, and my cycles are much more regular now, at least every 36 days - sometimes longer. I stopped taking metformin after the first 6 mths because I couldnt cope with the upset stomach.
Being on the pill for years masked the problem.