There are two prescription medications, Domperidone and Reglan, which have been said to increase milk supply, but they don't work for everyone. I know someone on another board who has tried both of them to no avail. It's not like you haven't already tried just about everything, right? Every drop is something to be proud of. You do what you can, & don't feel compelled to apologize for what you can't. If you also had supply issues with your first, there is a very good chance that it's not something that can be changed.
As far as PCOS goes, if you haven't already found it yourself, this is an excellent resource on the topic:
INCIID PCOS FAQ. Especially if you had problems conceiving either time you should check it out, but the condition is more than merely a reproductive one.