Chances of Pregnancy?

I just had sex today, I’m 8dpo. Period is supposed to come on the 29th. Glow said I have a 3% chance of getting pregnant, so my boyfriend just decided it was okay to finish inside me 😠 super annoyed with him, but that’s not the point. What are my chances of getting pregnant at this point in my cycle? Are they usually pretty low after ovulation? Should I buy a Plan B just in case? Please no hate, this has never happened before w my boyfriend so I’m just super curious!! Thanks!!

Edit: No we are not trying to have a baby!! At least not right now😂