Can Polyps In The Uterus Regrow?

I am 28 june 2010 I had polyps removed from my uterus following a 45 day bleeding with blood clots the size of the cardboard in toilet paper rolls......I think they have grown back because I very rarely have a period. I am wondering if that is causing a problem or if I am pregnant it says no on the tests but even at 6 months along with my boys it still didnt show even at the obgyn....could this be confusing my body. I have the very tender breasts and exhaustion.