Argh. Any time you put a penis in your vagina unprotected or without a condom, you've risked pregnancy. Those few thrusts can emit semen call pre ejaculation. That's enough to get pregnant. Is it likely? well, I don't know. It would have to be before or at ovulation time (sperm lives for 5 days) and it is a small amount of sperm. But you did still risk pregnancy. You will have to wait until your period is expected to take a pregnancy test. I doubt you are but yes, you risked pregnancy.