took plan b, period late by 1 day

me and my boyfriend had sex last saturday (december 4) and we used a condom but it didn’t break or anything, i took it just to be extra safe. i’m 17 years old and i took it when i wasn’t ovulating but my period was supposed to start december 8th. so the thing is i took the plan b exactly 8 hours later in the morning, and then i went to work and i saw dark red blood when i went to use the bathroom except it only bled for like an hour or two. but previously my cherry wasnt really popped all the way when we were having sex said so i kinda bled after it but it was a light red, and my periods are always dark red. so is it possible that the bleeding for 2 hours was my period from the plan b or should i take a pregnancy test soon. i was doing research and it says the plan b makes your cycle late, but on the package i saw that it makes your cycle come on time or earlier; and if you’re a week late you’re most likely pregnant. what should i do