Pregnant????

I’m between 15 and 17 days late (I use two different apps and each are saying differently). I’ve now taken two tests (first response) and BOTH came back as clear negatives. I stopped taking the pill about a month ago. I got my period when I was on the sugar pills but nothing since.

Since I took two tests and both were negative, is it safe to say that it’s just the birth control messing up my period and the tests are accurate??