Nobody is going to know for you cause we dont know your cycle, anything is possible, if this is not something that you wanted to be possible then you should have used protection. That is just my 2 cents hope you are not offended, cause that was not my intention, I just see soo many people that dont want it to happen and when it does they only have themselves to blame, there are so many forms of bc out there that there is no reason for unwanted pregnancies, with some exceptions of course.

Go to the doctor?

It's not that hard to call & set up an appointment. Its better than listening to everyones replies.

There is no way for you to know if you are pregnant one day after sex. You are probably not as your period is due sunday (mine too merry christmas to us!-lol) wait and see that's ll you can do.