Period confusion

I've been tracking my fertile window/ovulation time with glow for about 3 months now, thought third time might be a charm. It's seemed like I finally figured it out because my periods were like 33 days apart. My last period was December 26th so this morning I took a pregnancy test, and was waiting for those two pinks lines to show up but it was a BFN. such a slap in the face. It's now been 40 days since last period.. Just confused... And so over taking test. 😞