When did you start/stop pairing? You could try palpating her if you feel comfortable doing it to see if she even has follicles. Just because they locked up doesn't mean she was ready to ovulate or become gravid. Depending on follicle development, it may take months and months for her to ovulate (if she's even going to go for you).


Here is a RDR video of palpating.

http://www.youtube.com/watch?v=VDPZ1qSpca8