Three days late so far!

So I am almost three full days late on my period. Typically I start the morning of my expected period so it's pretty much like clockwork. I have taken a test each day and all have been negative. I'm wondering if I'm really not or if it's some how too early to tell? The tests say they are able to tell up to 5 days before a missed period.. I am trying not to get my hopes up but i would love for this to be it!