Anyone?

According to glow im 3 days late for my period. Im 17 years old and sex is new to me... I had sex on my ovulation day, it was my third time having sex, but we used a condom. We checked and made sure the condom didnt rip or anything afterwards and it hadnt. We didn't really finish because i was still experiencing pain and i wanted to stop. He says that he didn't cum or anything. So im just trying to understand what could be going on. All comments will be greatly appreciated.