I was diagnosed with PCOS while TTC #1 and put on metformin for 8 months.... it helped regulate my cycle a bit, but didn't get pregnant. I took myself off of it and about a year later decided to do a low simple sugar diet (based on two books, Fertility Foods, Jeremy Groll and Fertility, Cycles and Nutrition, Marilyn Shannon). It still took many months (maybe 5-6) to get pregnant, but I feel that the diet and exercise changes made a much bigger difference than the Metformin.... also, I am a normal sized woman and they increased the dose all the way to someone 2 times my size and it still was not effective.
I would research diet and exercise options before taking the medication.
SAHM to Chloe«- 6/2008 (10 lbs, 5 oz), Hannah- 9/2010 (9 lbs, 12 oz), Liam- 2/2013 (9 lbs, 6 oz)