Metformin and PCOS

Hey ladies, just wanted to ask anyone who has PCOS and was put on Metformin what dose worked for you and how long did it take before you started getting positive OPKs? Also wondering if anyone got pregnant after being on it? I unfortunately had a miscarriage at 18.5W on Memorial Day and so desperately want to get pregnant again. I was diagnosed in July with PCOS and started on Metformin 500mg twice daily and just increased it to 1000mg twice daily. Any input is appreciated. Thanks!