I had my period on December 9th and took emergency contraceptive on the 16th of December. I had some bleeding from December 20-23rd. My period was supposed to come today (if I was counting from the day my original period started), but it has not. Usually I can tell when I ovulate because my breasts hurt the rest of my cycle until my period, but I have no signs of breast tenderness or ovulation. I have taken plan b before and this has never happened. Please help me. What do I do?