shorter period?

Taylor
So usually my periods are 5-6 days but this one was only 4. The heaviness was about the same. The last time my boyfriend and I had sex was a couple days before I started. We used a condom and he didn't even finish because we got interrupted by my sister. The last time we had sex before this previous time was before my last period (not this past one but the one before that). We used a condom and we always check afterwards to see if it broke. It didn't and I still had my period. So I know there's probably a slim to none chance that I'm pregnant but I'm still nervous.