help?

I am patiently waiting for Aunt Flo to arrive I’m getting my normal signs but my app tells me my period is late by a few days BUT I’ve taken plan b a few times just to be safe ya know followed all the directions and normally I get a tiny period right after I take it and it kinda throws off my normal cycle (ps my cycle isn’t really normal haha but it’s always sometime at the end of the month ) and the last time I took a plan b was October/November bc I had a tiny cycle in November at the beginning of the month so I guess my question is, is that normal and is my app just saying I’m supposed to get one when I’m really not this soon? I have my signs at least a week before my period down to the day before I start it so it’s really up to my body I guess haha