Help!

I finished my last period on 4/16. I had unprotected sex on 4/19. Since I’m not currently on the pill, I took Plan B the next day.

I noticed my boobs were tender and fuller than normal. My period isn’t due until the 11th. This morning, I noticed I was lightly bleeding before cramps started. It wasn’t until tonight when I noticed this after I had gone to the bathroom. I’m assuming it’s just a piece of uterine lining.

Is this normal? Most clots I pass during my period are smaller and darker in color.