Confused

I am two days late for my AF. Per this app I would have ovulated the week of the 13th, I visited my fiancé the weekend of the 16, but again per this app, my prime ovulation time would have ended. Is it possible that if I did get pregnant, even tho I am late, that it wouldn't show a BFP yet because it hasn't even been a full 2 weeks? If pregnant, this would be my 4th. I have had sore breasts since two days after the last time we had sex, heat flashes, nausea, dizziness.. The whole 9 yards. I feel like I'm pregnant, but tests are negative and I'm trying to not get my hopes up 😂 anyone had a similar issue?