I've been on the combination pill (chateal) for about 10 months now. This month I've taken it pretty regularly at 10pm. On the second to last day of my active pills, I had unprotected sex. The next day, my LAST active pill, I was roughly 4 hours late taking it. I'm on my placebo pills now and usually start my period on Tuesdays right on the dot. My period still hasn't come. Should I he concerned?