Please please help!!

Hello all! Today has been my fertile week! This whole time I thought my ovulation date was today/yesterday. However I did remember that I had my period three days late last month. What does that mean about my ovulation date. Would it still be the date my apps have said? (and please don't be all like get a opk I know that for next time) just want to know if my chances are lower because I didn't have the right fertile dates or something