Hiya,
If you've been prescribed Metformin, are you diabetic? or is that just for the PCOS?
I don't know a huge amount personally but I have read time and again how women with PCOS have found relief from their symptoms with low carb. Try having a look at the marksdailyapple.com forums, I'm sure there is a regular lady on there who suffered from it and found great results on the Primal Blueprint.
I'm totally with you on the treating symptoms with pills rather than solving the cause.
My father is on Metformin for his T2 diabetes, I did a lot of reading on the drug and to be honest, in my opinion the actual evidence from studies and research has only proved to have a minimal positive effect. It certainly made no difference to my father's test results, and the long term side effects are not nice at all.
Hopefully someone will come along with first hand experience of PCOS to advise you, but in the mean time I will say, read like you've never read before! There is SO much information available now, albeit some good, some dubious, but informing yourself as well can only be a good thing.
Good luck to you & welcome to the forum
PS. I believe that low carb of whatever plan you choose, Atkins or whatever, will do wonders for you if you follow it to the letter.