help😭

okay. so me and dh had unprotected sex once. just once and he finished inside of me, on my "ovulation" day (so says my app) on the 4th of july. well ever since ive felt sick and nauseous... well i have a 27-28 day cycle, and im a day late (by my app) and i have had nothing but bfns... im not cramping or anything.. could i still be pregnant? or should i just wait for af too show?... i knew i was pregnant my last two pregnancies and tested early and got bfps... im just losing hope i guess...