Pregnant? Not pregnant?

I had unprotected sex 2 days before my period it was completely my fault and I didn’t take a plan b my period came on time Wednesday and I have been bleeding on and off dark brown dark red and red/ pinkish ? I have no idea what this is I’m scared and I can’t test yet it’s to early any ideas of what I’m experiencing? It’s not super heavy but it was heavy day one and it’s been getting very light now . Please give advice anyone ???? I know deep down I’m not but I can’t help and stress over this . ( I took plan b in October but my last period was good but now it’s crazy )