fertility apps?

im on the pill and i take it every day perfectly, but i still make my guy pull out bc i always like to have some sort of backup (pregnancy is biggggg no-no right now). lately he’s been begging me to let him finish inside and i want to, but i don’t wanna rely on just my pill even tho i know it would probably be fine. unfortunately the public school system has failed me and i’m not sure which times of the month i’m more or less likely to be pregnant. can anyone give me some advice, or recommend an app that can help me track which times are the safest?