My situtation is similar.....On Mon & Tues I had lots of CM, didn't get a + OPT until Wed. and again yesterday and at that point I had very little or no CM.......B/c I'm so unsure, we've just BD'ing every day since Sunday! (Getting sick of it, but hey.....has to be done! LOL)
I would pay attention to cm, for this situation, b/c sometimes those test don't work for some women at least that is what my doctor told me, she told me not to even waste my money on them, but so far I've had good experience with them. Most of the time I start having sex when I first see cm (3 to 4 days before ov & day of ov) , b/c you have a better chance of concieving. I am hoping for an BFP this mth also so I know what u're going though. Best of luck, on ur journey of ttc!!!!!