Tested Negative For Blood Test...

Hello everyone, 

I just got results back from a gluten blood test. They were normal. 

Is is possible to get a false negative blood test because I've been on a gluten free diet since January? Also I haven't accidentally eaten gluten for over a month before the test was taken. 

I'm pretty sure I have celiac disease because when I accidentally eat gluten (even very small amounts)  I get a severe reaction and am sick for 1-2 weeks. 

Thanks.