I was on the Depo shot(had two shots). My third shot was due 7/16/14 I did not take it. My period came on the 12th of every month even with the depo (last period 7/12/14). But 8/12/14 no period. Where/why has my period gone? I've taken several pregnancy test, all negative. I stopped the Depo due to prolonged bleeding, but now I'm 39 and Trying to conceive.

You need to consult with your OB/Gyn. You should have consulted as soon as you decided to try, but before going off the shot.

I have an appointment with my OBGYN Friday, September, 12 at 9:00.

Some women will find that it can take quite a bit of time for cycles to become regular after stopping depo. Unfortunately it is a common side effect. It's possible that this is the reason for the lack of a period.