First off, the blood testing won't be accurate unless you are on a regular diet and haven't gone completely gluten free.
Also know that just because you are tested for Celiac Disease and it comes back negative doesn't rule Celiac Disease out totally. There are many cirumstances of false negatives.(and some false positives and inconclusive tests as well) Dr. Peter Greene MD (Celiac Specialist) says that a patient may have 9 negatives in Celiac Disease testing, then the 10th test the doctor manages to get the proper spot of the intestine where the Celiac Disease damage (villi damage) shows up.
If you are tested for Celiac Disease and are negative...I would try the gluten free diet for a month to a few months to see if you feel any better. Also testing for other food allergies as well can be immensely helpful.