Metformin for PCOS

I am 26 and a mom to an almost 2 year old baby girl. I have been diagnosed with PCOS about a year ago and my husband and I have been trying for a baby number 2 for a little over a year now just about 2 weeks ago I went to see a doctor to try and figure out what is happening and why I am unable to conceive he put me on this medicine called metformin at 500 ml twice a day. This medicine is supposedly for diabetics but it has been proven for many women to work and to get there cycle going I have read online menu woman who are on this medication and who has been successfully able to get pregnant after getting their cycle. Does anyone have had or have experience with metformin if so, how long did it take to have your cycle start again?...so far I'm two and a half weeks into the medication and no sign of my cycle I am well over two months past due of my cycle and no I am not pregnant after taking multiple tests and they all are negative.