Because at the heart of PCOS is insulin-related issues, a lot of Drs will suggest that metformin be taken for the long term, not just while you're TTC. I would speak to your Dr about it again. There are a lot of us in the clomid/metformin thread if you want to pop your head in and say hello!

As for weight issues, low GI is the recommended plan for PCOS sufferers. I have had success with the Tony Ferguson program however as well which is a meal replacement, low GI, low calorie diet.