Advice !

So I've been tracking my period on this app since June and it hasn't been accurate at all. My last period I started aug 30th - sept 2nd . I had unprotected sex on sept 9th and according to this app my fertile window started sept 13-19. I've been feeling a little strange my breast are extremely sensitive I can't stand my bra and they feel heavier and fuller . I've also experience some really bad lower abdominal pain on my left side . Can it just be a sign of ovulation ?