Pleeease help! Important question

India
Im curious does anyone know if you can get pregnant if you have sex about a week before your period is due?? What are the chances %?? My cylce on average according to my app is 27 days with 6 days menstruation. I kno you have to be ovulating but Im not sure when Im ovulating. To my knowledge ovulation is the 14th day before ur next period or the following week following after ur last period. The plot twitst tho I took a plan B on March 17 (had sex that day and was ovulation day and he came inside of me) and had a period for about 15 days straight so im not sure if that messed with my ovulation but my period is back on track. I looked on the internet that a woman can get pregnant --->"Ovulation (release of an egg from an ovary) usually occurs between 12 to 16 days from the next period, although many women may ovulate anytime between the 11th to the 21st day after the first day of their last menstrual period. This is when the woman is known to be fertile, because if sexual intercourse occurs during this phase, the chance of become pregnant is great."<----excerpt from what i saw on the internet so my question is; is there any ladies out there pregnant that didnt concieve during the time they were suppose to be ovulating but AFTER?? Like a week before your period was due and got pregnant?? Oh yea the day i had sex was the 21st day after like the excerpt says...it was literally my 21st day😅 help! N thk uuuu💜 **also Im not scare to have a baby. Me and my boyfriend arent taking any precautions so so if a baby we're to happen it'd be ok I just wanted to know the chances or if it happend to anybody else..