Plan B

I’m kinda freaking out guys, so my period is late and I don’t know what to think. I did the naughty and yes unprotected but I took the plan b pill, like 2 days after. I was unable to get it quicker because of emergencies. After I took it like a week after I bleed a little and then I had brown discharge like when it’s old blood for a few days (2days). In total it was 3 days max of that. I don’t know what to think about that because I did the naughty right after my previous period had ended, took the pill and a week later as I mentioned before I bleed a little then had the brown discharge (old blood). I don’t know if it counts as a period and I shouldn’t expect my normal period on my calendar, or it’s actually a period. I’m freaking out here, I’m a little young to be having a child. I know plan B works 90% of the time if take it within the 3 day window. Some research says you can take it even as late as 5 days although it’s not recommended. I’m just worried. I don’t feel pregnant, or different in any way and it's been a while. I need someones opinion on periods?