Agreed. Sex in the week before your period is due is unlikely to result in pregnancy as the egg comes at ovulation 14 days before the period and is good for only one day. Also you would be complaining of other early pregnancy signs by now. If this was your sexual debut your hormones might have been upset enough to result in a late period this cycle. Download a period tracking app so you become familiar with your fertile window. Stock up on condoms if you think a repeat is possible. Good luck!
I don’t think so since you did have a period after you had sex already. Take a test if you are late.