Given that lab result--
--the endoscopy is a good idea, as evidence of villious damage is the gold standard of celiac diagnosis and that can only be obtained by endoscopy.
The anti-transglutaminase IgA antibody test is the one most specific to villious damage of the small intestine (some of the other assays in a celiac panel are more sensitive but less specific than that one).
Also, an upper and lower endoscopy usually means they are going to look at your esophagus and stomach (upper) and duodenum and upper small intestine (lower). The latter (lower) is much more likely where evidence of celiac might be found because it involves looking at the small intestinal villi. Still, make sure they take samples from various locations--8 to 12 is better protocol than just one or two--as damage from celiac can be patchy and hard to find, especially in early stages, and is sometimes missed when insufficient samples are taken.