So I have a question?

(Sorry TMI)

Ok so I started my period on Monday (07/22/2019) it started light and in the middle was medium. I normally have a 5 day period but I stopped a day early with just spotting 3x today. I know it impossible for me to end up pregnant so I need to know what’s going on I had sex the day before my period and he ended up cuming on my vagina and when he help me clean up he wipes it up inside me now I’m just curious to y I stopped a day early any thoughts

Please no negative comments just looking for answers thanks in advance