The fertile days of the menstrual cycle are considered the 2 days before and the 2 days after ovulation. If you had unprotected sex 3 days after ovulation there are less chances of getting pregnant ... but you can never be sure about the precise time of ovulation is you are not monitoring it (OPKs or basal temperature measurments for example). That’s why you should take a home pregnancy test to confirm or exclude pregnancy.