Uh confused please help..

Angela

Last month my period was late by 5 days, took a pregnancy test and it was negative. Eventually AF came. This month I am now late by 4 days and I tested yesterday and BFN and no signs pr AF yet, just really sore full feeling breasts. It’ll be a year in May since my Mirena IUD came out and I’ve had regular periods since then.. could this just be late side effects of the birth control removal or idk maybe I am pregnant idk.. HELP..