Hi Babe79
Don't know if you know or not? I havo e positive OPK for 4 continuous days and on the 4th day, I switched to another brand to test and it came out negative. On 5th day, my BBT shot up from 36.25 to 36.52. FF recorded my ovulation on 6th day.
What I mean is that though I have OPK +ve, the egg din manage to get through the gate. It only managed to "squeeze" itself out of the gate after a few tries over a few days..Hence, you most probably have ovulated much later and HCG is not high enuff yet. This is my suspicion.
Btw, did you use FF to record your BBT?