period smell no period

So I smell like I'm about to start. I start tomorrow according to this app which is usually spot on. I'm worried though because I had unprotected sex the last day of my fertile window. The 21st could I be missing this period or is it about to start? I've been having early pregnancy symptoms which are similar to period symptoms too. My DH and I have been trying and I don't want to waste money on tests. Both our other children we didn't show a positive test til we were finding out gender. Had to get blood work. I'm just impatient and don't know if I should expect AF or if I'm just too excited thinking this could be the one I miss. Any similar events or advice??