I was supposed to start Jan. 5th. It's now the 22nd and no sign of AF whatsoever. I have taken 7 pregnancy tests and got a blood test Tuesday. All including my blood test was negative. We have been trying for a year and I really thought that I was pregnant but having your blood be negative is like a huge slap in the face. What could be going on? Why am I so late and not pregnant? How long should I wait for AF before I become concerned?