I had sex 3 days ago and I know for sure he let go inside of me. My period is due in 3 more days but I'm currently bleeding

Any time there is penile insertion there is the risk of pregnancy. So yes you could be pregnant. You need to wait until about 2 weeks after you miss your period to know.

I'm currently bleeding ?its light pink. In stead of red like it usually.

It sort of like I'm spotting but but again I only had sex 3 days ago.

The spotting could be anything, as ScottGem said, the best sign is a missed period.