So me and my boyfriend had protected sex on November 28 but since I tend to be very paranoid at times I took the plan b pill the next morning. I got my period 5 days after that on Dec. 4th. We had protected sex again on Dec. 13th but he didn't cum at all so I didn't feel the need to take plan b to be safe. I was supposed to get my period on the 1st of January but I have not started yet. Should I be worried?