No. HIV is not easy to transmit and it is easier for a female to get it then a male in a hetro relationship. Use condoms with waterbased lube and you should not have too much of a concern.
Your 6 month test was well beyond conclusive if 6 months ago was the last time you had unprotected sex with her.
And it is entirly possible for one to be negative and one to be positive for years of unprotected sex, but not a wise thing to do because it can take only 1 time.