It sounds to me, based on what you were prescribed, that your doctor
thinks you may have polycystic ovarian syndrome. This is a condition in which a hormonal imbalance in the body caused unpredictable and irregular ovulation from the ovaries, which makes it very difficult sometimes to conceive.
Provera is a medication that is used to induce menstruation in those who are having very irregular periods. It will not actually help you conceive. Metformin, on the other hand, is often used in women with polycystic ovarian syndrome to try to normalize the periods and make it easier to conceive.
If you have not had any luck, I would definitely suggest that you go back to see your OB GYN doctor for additional advice. In addition to metformin, sometimes taking a birth control
pill for a few months can "reset" your ovaries and get them back on track. Additionally, there are other fertility medications that are used in women with polycystic ovaries
when they fail to conceive with metformin. On the other hand, your doctor may just want to wait a bit, since you have only been trying for 6 months, and you may just need a bit more time.
Either way, talk to your doctor!