Coming off birth control

So I came off birth control a little over a month ago. It made my periods irregular, some months I would have one, other times not.

In terms of ovulation, should I be going by what the app expects? Or could I have ovulated at any point because my periods were irregular? I’m 3 days late for my expected period, all tests coming back negative, I’m just holding on to the slim hope that I’m still in luck this month.