No Protection during Period Sex

Alright, my boyfriend has been pushing this lately & I've always been opposed to sex on my period in general but gave it a shot.. he did not pull out due to the notion pregnancy wasn't of concern while on my period. But, I know sperm can remain up to 5 days or so... In any case, it was day 2 of my period and although it was lighter (my period cycle is D1 Heavy D2 Medium D3 Light D4-5 Spotting) Well my period stopped late Day2 after sex. And I haven't had any spotting or medium-sized flow like usual. My question is has anyone experienced this? A change in your period if you have period sex?! I mean wtf hahaha