If low estrogen is an issue for you I would suggest that you read at least one of the books by Dr Vliet (she has a recent one especially about PCOS and there is new one (I think it still is in the works) on Estrogen. If the Estrogen one is not available yet, "Screaming to be Heard" is older but still a good overall reference for female endocrine health - with some emphisis on Estrogen decline and Menopause.
Don't let the word "menopause" turn you off even if you are in your twenties - a lot of the information you are looking for about low estrogen might be found in books about menopause. If you can't find the treatment that you need for PCOS w/ low estrogen it might also be worth it to see Dr Vliet - her website is
www.herplace.com - this is something specifically that she deals with.