Not even a year

So I finished rads the day before Thanksgiving, started Tamoxifen in Dec.  went for my Mammogram today, and ended up with a biopsy.  So grateful that they were willing to work me in, and just get it over with.  Should have results tomorrow or Friday. 

To me, the mammo pictures look JUST like my other ones.  I realize there is no use asking many questions till I have more info but the one that just is right there is HOW THE HECK CAN THAT BE?  How could it be cancer if I already had SIX MONTHS of chemo?!?  I know the rads didn't hit the side we are looking at now, but surely somewhere that chemo should have taken care of cancer in EITHER breast?  

 I'm guessing if it is cancer, it must be a different sort, to survive AC and Taxol.  Any words of wisdom?