Unless he had semen all over himself when he penetrated you, then i'd say you have a very low possibility of being pregnant, but it's not totally impossible for it to occur. If you want to test for pregnancy, you would just need to wait and see if your period arrives - there are pregnancy tests you can take if your period is only 1 day late. But try not to stress over things if you are, because that could make you miss your period.
I don't know if you and your guy use protection, but if you're worried about getting pregnant, definitely use something. Aside from abstinance, your next best bet is spermicide, condoms, and birth control.
Good luck to you, hon. Try not to sweat it, okay?