I hope you don't mind if I butt in here...I'm not officially on SBD but I am on a lowcarb/complex carb plan.
One of the main factors they discovered about PCOS is Insulin Resistance. A lot of women with PCOS have been put on Insulin Sensitising meds like Glucophage and/or switched to a low carb way of eating and it has brought back their periods or regulated them - me being one of them!
I'm not sure how it would 'work' in conjunction with BCP's as I was always told those periods were not 'real' but were withdrawal bleeds from being on the sugar pills or no pills for the week.
It might not hurt to get some bloodwork done to check for Insulin Resistance and PCOS. There is a good site which has lots of info and lists tests you should get done at http://www.inciid.org/faq.php?cat=in...ity101&id=2#76
There are also lots of support groups for PCOS on the net if you do get a diagnosis.