Chance of being Pregnant?

My boyfriend (16) and I (17) had sex almost 2 weeks ago but we used protection and neither of us finished (since it was a spur of the moment, afraid of gettting caught kind of thing). And I know sometimes eve is off when it comes to my period and I've been stressing like crazy this past week about our schools Homecoming (which stress usually leads to my period being late) but it's by 7 days now (even though I have the symptoms of my period) but I'm just a wee bit concerned about being pregnant even though I'm most likely not. Any thoughts?