Cycle day 55 no sign of period

I've been diagnosed with pcos. Been taking metformin for 3 1/2 months now been have my periods on time July August September was all on time...my fist day of my last period was September 25,2014 never got period yet...took hpt and bt about 2 1/2 weeks ago both bfn...has anyone ever go through this and still be pregnant....

Mind you have frequent urination and tender breast