help!

jackie

i had unprotected sex on feb,1 i took a plan b the same day and i usually start my period around the 3rd or 5th of every month, i haven't got my period and is feb 15 now , should i be worried or is the plan b effect? now, the only thing i feel is that my boobs are sensitive at times, only stomach aches and thats bout it , i kinda feel somehow likely cramping feeling at times but no sign of my.period, should i do a pregnancy test by now ?