From the details in your question, it seems highly unlikely that you are pregnant - getting your period two days later means that you weren't ovulating at the time that you had unprotected sex. Your period being shorter than usual is not reason enough to suspect that you could be pregnant in this situation.
If, for some reason you're still not sure, take a pregnancy test.
Don't forget to stay safe in the future - if you're not sure how, consult your doctor!
Rachel