Quick question y'all . Oh gm btw

Bella
Do any one know how the % thing work on here my app said today was my most fertile day An I hav 19.2% chance of getting pregnant but yesterday my chances of getting pregnant was 28.9% is my app wrong or am I missing sumthing cuz I thought 28% would be a better day to conceive then 19% idk Sumone help 😱😱