Help!!

Anna • married to the most wonderful husband in the world, a mom to a beautiful angel baby and my handsome rainbow baby boy grason j.Green!!!!💙💙💙 23 years old

I had a miscarriage the 13th and my SO and i have had sex the next week where he has finished in me... but my question is i have been feeling off lately is it possible to get pregnant so quick without having a period yet and when do i know i need to test???