Provera/lysteda (oral tablet) for heavy periods?

I can not seem to figure out how Provera is supposed to work (Lysteda works similarly)..here's my story:

I'm 40 yrs. old, always had light/short periods even with low counts but for the past year have gotten much heavier periods with clots that last longer. My hem prescribed Provera tablet (5 mg x 2 a day) and my gyn said Lysteda would work similarly...take the day my period starts for a few days. So i did, bleeding miraculously stopped within a day. now i stopped taking the pill (after 4 days) and bleeding back, but how do I know it won't be heavy and long period again!! I don't get how delaying the bleeding helps, and I can't get any of my drs. to call me back

Anyone have experience with this??
Thanks!
Laura

www.nlm.nih.gov/medlineplus/druginfo/meds/a682470.html
www.nlm.nih.gov/medlineplus/druginfo/meds/a612021.html

I actually posted AFTER I have read all the material there is to read online, and as I mentioned, I did get it checked out and doctors don't seem to be concerned. But for me it's very heavy bleeding and I don't understand how stopping bleeding now just to have it come later helps. It's not like I didn't have periods and needed help getting them, they come at regular increments.

Does anyone know about this issue?
Thanks!