Very late AF but no BFP

L • Mommy of 2 to the best babies in the world.
My AF is always on time, if anything it comes a day before or a day after my 28 day cycle. This cycle my AF was due 7 days ago, last Monday.. I took three pregnancy tests already (on day 3, 5, and 7) after my missed AF.  All three were BFN. I purchased them at the dollar store (we have been TTC for about a yr and a half, so named brand tests were getting expensive LOL).
Weirdest part is I think I ovulated twice this past cycle.. Is that even possible?
Can there still be a possibility for a BFP? Should I invest in a better named brand test? 
Baby dust to alllll!!!