No Period HELP!

I am 16 have a boyfriend we have sex quit often but it is unprotected .. My period never comes on the exact day .. But according to my tracker I am 7 days late .. And I'm starting to get very concerned .. I just had prom and have been stressing lots about that .. And have been around a girlfriend almost everyday getting ready for prom is there anyway either one of these can make my period this late ... Or is time for a test ? HELP!