I have PCOS, I am now 25wks pregnant, this was a natural pregnancy. I was due to start on clomid but found out I was pregnant the day before I was due to commence. I have 2 periods a year if I am lucky. I have been told by many people that you have the best chance of falling pregnant straight after you come off the pill, whether or not that is true I don't know. It took us nearly 12months to fall pregnant, I was diagnosed with PCOS a few years back and was told chances of falling pregnant naturally would be zilch, and we are very lucky considering I only ovulate twice a year! I was actually considering cancelling my appointment with the specialist becuase we had decided to take a break and I would go back on the pill for 6months and not think about it, but it seems it all fell in to place.
Just being healthy in general, if you smoke, quit, cut back/quit on alcohol, eat plenty of fruit and vegies, exercise. I lost 30kg to get to a healthy weight and it still made no difference to regulating my periods and ovulation, I think it all depends on the individual person and case. I also started taking vitex to try and shorten my cycles and when I had doubled my dose I found out not long after I was pregnant.

Good luck to you, baby dust your way when you TTC.