Could I be pregnant ???HELP

SOMEHEAT

Hi I'm 19 years old and AF was supposed to start 4 days ago on the 10th and my LMP was January 13th to January 19th and me and my partner had sex around the time of my fertile window which was from the 22nd to the 28th but I've taken 2 pregnancy test the day of my missed period and they were both a bfn ... I'm not sure what to do could I be pregnant or should I test again??