Late period, BFN

Lauren
So my period was due on the 6th, I've had every pregnancy symptom in the book apart from sore boobs - which is all completely opposite to my PMS symptoms. I have done 3 tests including clear blue digital and all negative. I even had brown spotting 4 days before my period was due so I was pretty confident I would get a BFP! When I was pregnant with my first I got a faint positive the day before my period was due and a positive digital the day it was due so I'm very confused, I am never late for my period! Any advice or similar stories with outcomes? Thanks in advance.