AF only 2 days..

Not sure why but my period only lasted 2 days when it's normally 4 days. I cramped a full day before my period actually started and then the first day. The second day I had no cramps and still bleeding but not as heavy as normal and then today it was gone..just light pink when I wiped but nothing else. Is this normal? I did have sex on cd 16, 17 and 18 but I know it's too close to my period start date..anyone experience this before? And should I test or no?