HELP NEED ANSWERS ! TMI

so every month my period would come around the same day . last month it came on the 11th of July and two months ago it came on the 10th of June. now this month August my period is late only about 2-3 days late. I took a pregnancy test yesterday and it came back negative. I've heard that you should always take a pregnancy test a week after your missed period , but I wasn't sure because my first pregnancy last year it was accurate with positive on the day I was suppose to have my period. also I've had plenty of unprotected sex with my boyfriend , but he does the pull out game. but ive read that you can also get pregnant with pre cum which he does Everytime we have sex .anyways here's a photo that was taken a few minutes ago .. keep in mind that I'm late 2-3 days . so what could this mean ??