Hello people

I need advice regarding the ovulation test .. last cycle I brought clear blue advance digital ( which was very expensive) and confirm the ovulation(fixed smile) on Aug 19 and this app gave my ovulation day on 20 Aug which is very similar Unfortunately we didn’t made it and AF came I’m wondering if I should buy ovulation test again? Or just go with this app knowing that my cycle is very regular ..( all the ovulation test even easy @ home are expensive in my place )