Should I Worry?

I lost my virginity on December 10th, we used a condom but I wasn't on birth control. Two days later I got the birth control shot. On the 23rd of December we had sex again, twice. We didn't use a condom but I did use the Plan B pill imeadiatly after to be safe because my birth control shot wasn't completely effective yet. He also pulled out each time. My period was supposed to start sometime this week, projected on the 24th or 25th (today)...but I haven't gotten it yet. I have some symptoms like sore breasts but not much else. Should I be worried?