First time

I’ve always been straight until i met my girlfriend years ago, but was never interested in any other female but her. A couple months ago we started dating and we finally had sex with a strap for the first time and it was a little blood after and on the sheets but i wasn’t on my period or about to start and the blood was gone a couple hours later and it wasn’t even like spotting or anything. I know i haven’t had sex in almost 4 months so could that be why ?