Please Help Me Understand PCOS

On Feb. 16 I had my second first trimester m/c and decided to see a RE. So far my blood work has come back normal. I have regular cycles (on and off b/c) and I ovulate regularly...because I have no problems getting pregnant. I went off bc Dec. 1 and had my first period Dec. 31 and got pregnant on that cycle. I did a fasting blood work and my glucose came back normal, which I've never had a problem with that. My insulin however (didn't know there was a difference) came back as 42. My RE called and started me on Metformin (500mg...first week one pill with evening meal; second week two pills with evening meal; third week three pills with evening meal). I go back to get my insulin checked April 16. I was shocked! The nurse said I probably have PCOS because of the high insulin and that could be a cause for my m/c. I am producing bad eggs and not having a viable pregnancy. We are still waiting on the chromosome results (takes 4-6 weeks) and HSG to see if I have any scar tissue from the D&C I had due to my first loss. What is PCOS? Can you have it and have normal periods and ovulate normal? I've tried to read about it and the only thing I can find that I have symptoms of it is the insulin resistance and I have gained weight and carrying it in the middle. But, I haven't gained but maybe a 2lbs a year, but it does seem hard to lose it. March 4 my HCG was "-". I haven't gotten AF yet after my m/c and was wondering if it's normal to wait this long. Is PCOS going to put a hold on trying to get pregnant again? This is all new to me and I'd appreciate any help I can get.