If I’m usually regular, why when my period doesn’t come, the app pushes back my ovulation.

My original Af was the 9th, saying that I ovulated on the 27h (or so). That didn’t happen..so I clicked “my period is late”.

Then it said my period would start the 12th.. pushing my ovulation a few days later...then no period on 12th...so on and so forth...still no AF. Still no BFP?