Endoscopy

If you have not been consuming any gluten, your small intestine villi should revert back to healthy.  If you have been consuming gluten, and you do have celiac, the villi supposedly would be compromised (though I think the only way they can tell for sure is to have all your samples lab analyzed with microscope and all, which usually takes a few days).  So I don't think you'll really get an accurage diagnostic until after the endoscopy results come back from the samples taken.

If they still come back "normal" and you feel better not consuming gluten, then that's really all the proof you need.  Avoid the stuff.  Maybe you are one of the millions that are gluten intolerant.

I did the blood test and endoscopy for celiac, both came back negative.  I did them because i have a big family history of celiac and gluten issues, as well as all sorts of crazy food allergies and intolerances in my family.  So, what the heck, might as well be tested before I stopped eating it.  I ended up with Ulcerative Colitis.  I sometimes wonder if I had spent my life avoiding gluten, would I still have colitis?  Can't ever know the answer, but avoiding gluten (and pretty much all grains/starches, actually) made all my intestinal gas go away!  Hooray!