late and short period

B0SSLADI18

I was suppose to start my period on the 15th but didn't start until the 21st. my period cycle is 5 days it was only 2 1/2 days long. is it possible. should I wait two weeks to test. untested prior to my late period on and after the 15th because it was late and it was negative, but my period was short this month. I've been having horrible backache cramps and nausea.