It could perhaps be paranoia of some sort– I have anxiety, and many times I worry about things and then get a gut feeling about it and listen to that a lot and it turns out to be false. So perhaps you are so worried about it it is making you feel that it is true?
I’m not sure when you hooked up with this person, but I recommend waiting to see if you get a period (if you usually get a period monthly). If it does not come around a time you would normally have one, then I recommend waiting a week and taking a pregnancy test. Or making an appointment to see a doctor about getting tested.
Hope things go well for you!