E.M.
Well a couple of things:
I didn't get my period for about 13 months after Evan was born. It has yet to become regular again, so personally I went on a low estrogen birth-control pill and didn't get it at ALL. I went off of that for a month and it returned.
But my doctor attributed my non-period to stress of my son's surgery and just daily life. I would have a frank conversation with my doctor about everything going on with you.