All my symptoms can't be explained by vitamin D and ferritin being low. But all the tests come back negative. I had a relative who tested negative for celiac but later had to have intestinal surgery. She was diagnosed with celiac based on the damage they found to her intestine. I've heard of many cases of false negatives from looking around online, especially on these forums. Sometimes it's really hard to get diagnosed.
I know this process is really frustrating but do lots of research and don't give up!
I've found in my research that there's a correlation between epilepsy and celiac disease. My younger sister has blood-test confirmed celiac (her numbers were so high they didn't bother to do a biopsy) and she has migraines as well.