Missing period on Peogesterone

I've had massively irregular periods my whole life, and recently (about three months ago) started taking a Provera substitute (medroxyprogesterone) 10 mg. The last two months, within four days of finishing the pills, my period came and everything was fine. But, I'm a worrywart and I'm freaking out slightly because it's been nearly a week. Anyone else experience this?