On January 10th my boyfriend and I had sex and the condom broke. We did not realize the condom broke until about 5 minutes later. He did not ejaculate inside me. He immediately went to the store and bought me Plan B (because we know that it is possible to become pregnant with precum). I took it within 2-3hours of intercourse. My period was expected to arrive on January 15th (5 days after this occurred, and I am now eight days late (today is January 23rd). I took Plan B on the 10th... so it has been 13 days since then. Should I be worried? The last time I took plan B blood arrived within 3 days. But, it was during a different time in my cycle. (around a week after my last period... not 5 days before my period like this time). Should I be worried that I may be pregnant due to precum? How long can it take for a period to arrive if Plan B is taken late in a woman's cycle?

Thank you!

Edit: Also, I noticed thick brown discharge two days ago that looked like it may have been blood? Or maybe not? I heard that this is a side effect of Plan B, or it can be a sign of early pregnancy?