had intercourse when expected my period and bled a dab then nothing ?

I had last period on 2-20 - I run a few days early each time so expected it on 3-17,18, 20th or so sine Feb short month- had unprotected sex with hubby on 19th spotted a little that night right after then nothing. Also having problem with sores where my cecarean scar is - from wearing pads waiting for period? putting neosporan on them - happen occasionally-its been 6 yrs since surgery! Could having sex when about to start cause you to miss your period? Or postpone it? Today is the 23rd- maybe just not enough days gone by yet? Help!