confused

Okay ladies, I need help. I am very confused. My boyfriend and I are not necessarily ttc but arent preventing either. af was due Monday November 6pth and nothing. I have taken 4 tests. 2 before af was due and 2 after. All have been negative and still nothing. My breasts are slightly sore and I have very light cramping every once in awhile but that's not a normal lead up to af for me. Has anyone else experienced something like this? I am just not sure what to do and at what point I should become really concerned.