No AF and BFN

Maria
Hello lovely ladies
My AF usually comes very regulary, usual on the day it's suppossed to. This month, it should have been here on friday the 20th, but she hasn't come and there are no sign of her. 
I took a test a couple of days ago, got a bfn, and took another one this morning (a different kind and brand), and again got a bfn. 
Have any of you tried this and/or have a good reason for my body's strange behavior. 
Have a good evening ❤