Is it in my head?

My period is three days late (and it has been like clockwork for the past 6-9 months on the same day). I have been having crazy insomnia and fatigue, back pain, frequent urination, and loss of appetite. I've taken three pregnancy tests (one prior to the day my period was due, one on the day it was due, and one this morning). All three were negative. I've tried a different test (First Response versus Clear Blue) and still nothing. Is it in my head? Has anyone else experienced this? What does this mean?