Welcome to the forum, @terrymouse! Your GI doc is correct. Going gluten free now will allow healing to occur in the villous lining of the small bowel such that the endoscopy/biopsy may not show the damage to the villous architecture that is characteristic of celiac disease. Since your celiac blood antibody tests results are on the low side and don't "scream" of celiac disease I think it is important to go forward with the endoscopy/biopsy while still consuming gluten to ensure it will not be a wasted effort. The last thing you want is to have two different test modalities that unnecessarily contradict one another. So, unless the continued consumption of gluten poses an immediate and significant threat to your health, my advice is to (excuse the pun) "gut it out" until the endoscopy/biopsy happens. There is also the option of temporarily going gluten free and then undertaking a "gluten challenge" in the weeks leading up to the appointment in September. Current guidelines for the gluten challenge are the daily consumption of at least 10g of gluten (the amount found in about 4-6 slices of wheat bread) for at least 2 weeks leading up to the day of the procedure. But I would certainly give it longer than two weeks to be sure. And in view of the fact that it could happen sooner if there is a cancellation, I would encourage you to not go gluten free until after the procedure if your health permits. By the way, what are your symptoms? What led you to investigate celiac disease as the cause of your medical issues?

I had an endoscopy where there was no visible damage but biopsies showed damage. I even asked beforehand if the endoscope had good enough magnification to see the villi!  I hope you get a clear answer from the biopsies.

I have an endoscopy booked for mid-September to test for Celiac. My gp seems convinced it is celiac and I should eliminate gluten right away, but the gastroenterologist I was referred to says if I'm totally gluten-free then they won't be able to detect celiac from the endoscopy, and I should load up on gluten 2 weeks before the test. So I guess I shouldn't eliminate gluten then? Or stop and start again closer to the appointment date. But I'm also on the wait list in case they can get me in sooner, because I'm losing weight. I don't want to have to go back and do it over again if I can help it. They also were unsure if there isn't something else wrong with my stomach, so that's a possibility. I don't have the details but from what I understood my blood tests results were positive but on the low end. So I'm getting mixed up here, do I go gluten-free or not? Would 2.5 months of being gluten-free make any noticable difference? 

Being low in B12, Folate B9, ferritin, zinc and copper sounds consistent with anemia which can often occur with Celiac.  What did your doctor recommend? What about your Vitamin D?  It helps regulate the immune system.  

@knitty kitty thank you I am exploring these options, I really appreciate all the suggestions and info. I am only slightly below the normal range for folate, zinc and copper. And in the low end of the normal range for B12, ferritin, and vitamin A. I’m good for carotene magnesium and iron, but I’ve been taking 400 mg magnesium daily