Spotting & AF is not due until 7/16

Carrie • TTC for baby #1

Hi everyone! AF is not suppose to be around until 7/16 (7 days) however today I notice blood. There wasn't a lot but there was some. This happened yesterday as well, very light. We are trying for our 1st so we did have sex on all of the days that I was fertile. Can anyone explain the spotting?? Thanks!!