% of getting pregnant before ovulation

Hello everybody :) 
My period started on the 31th august and lasted about 4 days, (shorter than the other ones). I had complete sex with my boyfriend on the 9th september, 3 days before my eventual ovulation. What do you think about it? Have I any chance to get pregnant? I have read that sperm can last 72 hours in the vagina, so to get the ovul when it is relased. 
I need opions please! Thank you to everyone. Have a good day 😘