Late Period. Anxiety. Had Unsafe Sex. Taking Xanax. Related?

I have been taking Xanax for anxiety in small doses for about three or four days now. However, I've had unprotected sex multiple times in the last month or two. My periods have always been very regular, to the point I can keep track on a calendar when they are expected and how long it will last. I'm now three days late and my friend insists it is because of the Xanax. Would it even be possible that it has made me late on my period when I only started taking it right when my period was supposed to start? I'm not on any birth control at all, and have not taken a pregnancy test.