Possible To Ovulate Late ?

The month of March I got my period on the 3rd ( it lasted for about 4 days) my cycles are never that accurate. On the app it said my ovulating week was from the 16th - 22nd. I had sex multiple times that month on the 8 , 20 , and 28. I’m currently pregnant when I asked my doctor when I conceived he said on the 30-31 of March meaning I ovulated a day before that. Is it possible I ovulated that late ? And got pregnant from having intercourse on the 28 ?