Thank You for your response I wiLL do my very best not yo stress about it. How soon will I be able to know for sure?
It is very likely you're pregnant. Semen can live in the vagina for up to 2 days according to my research. Take a home pregnancy test on the day your period is due. If it's negative but you see that you are late, test again a few days later.
But try to keep calm. It's possible that you are not pregnant but the stress may affect your cycle and make your period late.
Best of luck!