I’m so damn confused.. help girls!

Ok so my period always comes days after my predicted period time on this app like the app will say it’ll come June 1 and it’ll come June 4. So recently it said my fertile window started Sunday but for some reason I didn’t feel it or get any of normal cervical mucus to indicate that I was. So yesterday was supposed to be my last fertile day but I got more creamy white sticky discharge than I have through my whole supposed to be “ fertile window”. So what I’m basically trying to ask is , is it possible that my fertile window started later then what the app predicted like my period always do? I just wanna know because I am trying to conceive and when I saw all the discharge I took it as a greenlight and had unprotected sex with my partner.