I'm on CD 35 (19dpo) and I had a qualitative blood test which came up as negative. I know I definitely ovulated on CD 16 and my period was due on CD 28. I took my BBT this morning and it suggests that I have already ovulated. I'm only asking if my blood test was wrong as I've had really intense cramps in my uterine area and it's really starting to hurt. I read somewhere that some women don't show up on a blood test until the placenta takes over the production of HCG. Do you think that there's any chance of that?