You could be pregnant if you had unprotected intercourse , but also you can't be sure until you will have a pregnancy test , I would say , go and get one , since your period is shorter than usual and you feel tired .. you don't have to worry that if you got pregnant you will have the same problem as last time , because each pregnancy is different ,,, don;t worry about this, go and get a test and if it comes out possitive go and see your doctor . take good care !!!!!
A 2-day period is not a concern. A normal period can be 2-7 days long.