why did my fertility window change all of a sudden.

Janie • Mommy of 3 babies in heaven and a baby girl! 👼🏼👼🏼👼🏼🤱🏻💗
I got an alert that my fertile week on Mon. 9-19 through Mon 9-26. We are ttc a boy so we planned on having sex, Friday, Saturday and today (Sunday) closer to ovulation but... when I went to log into my account today my fertile days changed?? Help please!