No reason to even question that. Stress causes
periods to be late, diet can cause
periods to be late, a lot of things can cause a period to be late. Your symptoms are probably your period getting ready to hit you like a bus, i bet anything that your period will start in a few days.
THE ONLY WAY TO BE PREGNANT IS THROUGH SEX unless you did a turkey baster thing, but i doubt you would do that. So please dont worry about pregnancy until you have sex. You're perfectly fine.