Mrs., did you test with FRER? I'm in the same boat as OP, so stalking this thread a bit. I tested with FRER yesterday, estimated 12 days post O, and got a bfn
GVW, I say don't lose hope until she shows up. I did get 4 negatives after AF was due with my second pregnancy. I don't remember what tests I took though, that was over 8 yrs ago.