My last period's first day was January 17th. On the 26th, I had sex and the condom broke. I finally got a Plan B roughly 36 hours later. Now, I'm bleeding very lightly and the blood looks dark brown, and it's been going on for about 4 days.

From my research, this seems perfectly normal after using Plan B, but I've also been told that this could be a sign of pregnancy. Could I get clarification please?