Hpts - were they accurate?

Philana • TTC since 2008. Conceived twin girls in 2015 with IVF & delivered at 31+1. Surprise baby naturally conceived 02/17.
Hi pregnant ladies! I'm currently TTC and in my ttw. This is an ivf cycle for me and today I'm 10 days past my egg transfer date. My blood test is next Wednesday.
​I tested 2x using clear blue and both times were negative.
​It's pretty devastating. And I'm wondering if anyone's hpt was negative but their blood test was positive? 
​Thanks for your input. :)