Pregnant? But how?

Here is my issue. Me and my boyfriend had PROTECTED SEX a couple weeks ago. But my period is about 5 days late. I'm having the regular period cramps and pains but no period. I am not too worried about actually being pregnant since we used a condom from start to finish but I can't help but worry a little bit. The stress of this is obviously only delaying my period more but if there are solutions to what is happening to my body, I'm all ears.