Erin,
My Wondfos were negative at cd 25 of my mc but when I went for a bloodtest my hcg was still at 15.
Have you had a period yet? Or did you ttc the same cycle as your miscarriage?
If its the same cycle as miscarriage, then
A) you could be pregnant
B) you could still have residual hcg from the miscarriage
C) you could have a small amount of retained tissue producing hcg
Only some serial bloodtests and an us can tell you for certain.