So for any of you who use these, I am entirely confused. I typically use these with FMU, but I get nothing but negative results unless I test in the evening. What gives? I'm on CD 15, and I THINK I typically O on CD 16 (although last month I was a week late so I'm guessing I ovulated late last time). But I'm still showing negative OPK results with FMU. I'd think if I was going to ovulate tomorrow is at least be showing high fertility. Thanks in advance for any help you can offer.