10 days late, negative blood test

Sarah
Hi all!
My husband and I have been trying for over a year since my D&C last June.  I am currently 10 days late and had a Hcg blood test yesterday that came out negative 😔. My doc said we will test again after thanksgiving.  I, of course, was hoping for a positive.  
Has anyone ever had a negative blood test be wrong.  
Thanks for any insight...just want know something isn't wrong with me.