AF Due 11.14.14

Samantha • 27. A Mom of a 5 year old DD with 2 Angels in Heaven. 💔👼🏼👼🏼
Tested 11.13.14-Negative
Tested 11.16.14-Negative
Now the 18th and nothing. I've had sex to see if it'll jump start my period because it normally does and I'm still waiting... I'm so confused. Could the HCG still be undetected? I used ClearBlue pregnancy test both times. I've been actively trying and this is driving me crazy!