I don't have PCOS, but I know that it makes weight loss more difficult. I'm just wondering what your eating plan is now? When I was looking up information about nutrition, I was interested in going on a low-GI diet, and it's good for insulin resistance and PCOS. Although you probably are already aware of it, I thought I'd throw it out there. This link is helpful. http://www.the-gi-diet.org/glycemicindexchart/
I think there's also a "chicks with challenges" message board for PCOS on this site, I'm sure they can give you a lot of great information.
As for feeling ashamed and not going to the doctor... heck, I know the feeling! But if the Metformin is going to help you lose then it's worth a little temporary discomfort. I'm sure that your doctor would rather see you be successful in your weight loss than chide you for gaining a few pounds.
Hang in there!