Period/pregnancy/ovulation

I've been off the pill since end of November and since then I have had regular periods to the day. Last period started 16th Feb, therefore I was meant to ovulate according to the app on the 2nd march, however I never got a positive ovulation test (testing once a day, I know now I probably should have been testing more) anyways we had sex every other day around that time.

My period was due on the 16th march, I had a wipe of blood this morning but nothing since. I took a pregnancy test which came back negative.

Not a huge fan of not being able to work out what is going on with my body and probably stressing over nothing but any advise as this is the first month we have ttc.