It's my understanding that you can O without getting your period, just like you can get AF without O'ing. If that were me, i would give it more time. After 6 weeks, the drug is just starting to build in your system and your hormones are still regulating.
IF you decide to induce a period rather than waiting it out a few more weeks, have you considered natural progesterone cream rather than provera?
There are a few reasons why I am not a fan of provera, particularly for women on Metformin.
1) I have read in a few places that Provera can affect the blood sugar of diabetics. If you are insulin resistant, this may be problematic in keeping your insulin/sugars under control.
2) Provera is a Synthetic form of progesterone. It has side effects that real progesterone doesn't have.
See:
http://www.wanttobewell.com/articles7.htm
See also: "Provera is not Progesterone"
http://allonhealth.com/natural-proge...ogesterone.htm
I have read enough articles on the differences between provera and progesterone, that I'd personally rather take the real McCoy if given the option.
Good luck and hope it helps!