unusually light and virtually cramp free, Could I be?

ok here's my story. My periods have been regular up until this month, the first day of my last period was on the 14th of last month, they usually last 5 or 6 days. This month i didnt see anything until 6 days after i was due for my period. It wasn't even a normal flow, it was unusually light and virtually cramp free. I took a pregnancy test 4 days ago at the docs office and it was negative. Could it have been to soon to register? ive been pregnant once b4 but miscarried at 3 months. that pregnancy was not detected by the urine OR blood tests. So im worried that the same thing may be happening again. I have NEVER cramped after having a "period". Please help!