Should I take a pregnancy test?

Catherine
Been on the pill for about 4 months. Period is regular and comes usually Tuesday but mostly Wednesday. And I get cramps before so I know it's coming. Had sex 2 weeks ago and for some reason I'm a little skeptical about whether or not this pill is working for me. 
Today is Wed and no sign of my period.
Should I take a pregnancy test? It's been two weeks and I'm technically late for my period.