Not normal for me... COMMENT PLEASE !

Should I be worried?? /:
I know it's dumb of us, but me and my boyfriend do have unprotected sex..quite frequently. Sometimes multiple times a day when we see eachother. (I'm 17, he's 19.) 
Yes, he pulls out. 
Yes, we are aware of precum.
My period was about a week late but when I got wasn't dark and heavy like it usually is... It wasn't "barely there" light but not nearly as heavy as I always get my periods. And my periods always last about 8-9 days to be fully, completely off of it. But this time I'm off of it after only 4-5 days. This is not normal at all for me... Should I be worried about pregnancy?? /: Comment please.