Hi Showstopa,
In a word, your doctor is "nuts", because he obviously doesn't care how much you might suffer, because of his recommendations. If I were in your shoes I would run, not walk, away from his office, and never return. IMO it should be illegal for doctors to recommend a gluten challenge for patients, just so they can "officially" diagnose celiac disease. It's bad enough to have to be sick free of charge, but to pay someone (your doctor) for advice that will surely make you sicker, seems ridiculous.
Regarding your biopsy report results:
First off, one's intestinal lymphocyte count is never zero. It might only be 2 or 3 lymphocytes per high power field (hpf), but it is never zero. Either the pathology report did not state a count, or your doctor is stretching the truth (to put a lie in polite terms), because it is never zero. When you receive the pathology report, you will see what it actually reported. Probably it simply says that your count is below the level that's considered diagnostic for MC (but that's a long way from zero). Since you have changed your diet, I would expect your lymphocyte count to be down, but I surely wouldn't expect it to be zero. If your lymphocyte count were actually zero, you would be sick all the time from every virus and bacteria that came along, because your immune system would have no guards on duty to prevent infections from getting started.
Secondly, haven't you ever wondered why there is no test to diagnose "IBS"? It's because "IBS" does not exist. "IBS" is a fabricated disease that GI docs invented because it sounds so much more professional to say,
You have "IBS!", than to keep having to repeat over and over again, "
I don't have the foggiest idea what's wrong with you, but nevertheless, don't forget to pay my outrageous bill on our way out."

"IBS" is typically either the early stages of celiac disease or MC, or simply an overlooked diagnosis (often because of a failure to take biopsy samples during a colonoscopy exam, or a failure to even consider those 2 diseases).
The reason why doctors thought that MC was a "rare" disease for decades was because they were told in med school that MC was a "rare" disease, so they simply didn't look for it. If you don't look for it you can't find it. So that became a self-fulfilling prophecy. The same fallacy applies to the old claim that African-Americans, Asians, and Caribbean residents almost never have celiac disease — it's a self-fulfilling prophecy, because doctors don't look for it.
Most sources state that celiac disease is rare in African Americans and those of Asian and Caribbean background, however data also demonstrates that African Americans susceptible to the disease can frequently be misdiagnosed. Based on information from several reputable sources, some African Americans with Type 1 diabetes have more potential of developing the illness than others, but many African American Type 1 diabetics test negative for the gene predisposing them to celiac disease. These findings notwithstanding, a general under-diagnosis of celiac disease in African Americans is reported in the literature.
Is Celiac Disease A Threat For Blacks?
If your doctor wanted to rule out celiac disease, he should have done that when you first came to him, before you changed your diet. What's his excuse for waiting so long?
If I were in your situation, I would have to think long and hard about doing what your doctor is suggesting, because while it would make him very happy to either diagnose celiac disease or rule it out, you would be the one doing all the suffering. The celiac tests have very poor sensitivity, so you would have to eat gluten for at least 3 or 4 months (or more) in order to cause enough damage to your small intestine to provide a reasonable chance of triggering a positive celiac test result. And if you don't continue eating gluten long enough, you will receive a false negative test result, meaning that you would have gone to all that trouble, and put up with all that suffering, for nothing.
And even if the test result turns out to be positive, the only thing your doctor could tell you would be that you need to avoid gluten. But you already know that, so why go through all that suffering? An official diagnosis would be a feather in your doctor's cap, but it will provide absolutely no benefits for you, because you don't need a diagnosis to avoid gluten. You can avoid gluten without a diagnosis, and you can avoid gluten without a doctor's blessing. And none of us needs to be as sick as a dog for 3 to 6 months (and recovery afterward would probably take just as long) just to make our doctor happy.
At least that's the way I see it. I'm pretty sure that I'm a celiac, because I have a celiac gene, and I had all the symptoms, but I'm not about to do a gluten challenge at this point, because I never want to be that sick again. I don't care whether or not I have an official diagnosis of celiac disease, because as long as I totally avoid gluten (and the other foods that cause me to react) I'm healthy, so why should I care about an official diagnosis — it's a moot point.
I notice that you did not mention avoiding soy. Many of us here are sensitive to soy, and those of us who are, typically are extremely sensitive to it. There is also the possibility that your diet may be cross-contaminated with gluten. If anyone else in your house uses wheat flour, then your food is almost surely cross-contaminated with gluten, no matter how careful you and they might be. I'm speaking from experience here, because I found out the hard way that it's impossible to keep flour dust from settling over everything in the house, including my (and your) food.
I hope that some of this is helpful.
Tex