For ethical reasons, I've been vegetarian for 18 years and vegan for 2 years. I found out (blood tests positive, endoscopy/biopsy 100% conclusive) i was a celiac around 4 months ago.
My symptoms were mainly terrible heartburn, arthritis, and depression.
i've had my ups and downs on the diet, and the downs have come after specific instances where i can figure out where i wasn't careful enough (eating out, at relative's house). Overall, though, I've been doing better.
i spoke with a nutrionist and a GI specialist and am doing very well nutrion-wise with Tofu, brown rice, many beans (especially chick peas-- my fave), blackstrap molasses taken daily as a supplement, and more nutbutters. I've had lots of bloodwork done at the hospital and all of the nutritional markers they can measure (folate, vitamins, etc.) show up very well for me. I also take a good quality gluten-free vegan multi-vitamin, Cosamin Ds, and Calcium Citrate.
i am a 26 year old male athlete, and have had zero problems getting enough and varied enough protein...
you just need to be educated and fastidious about what you're eating. I do, however, miss my veggie burgers and seitan stir-fry!!!
As many of those on this board experienced, my downs have been much worse than prior to me starting the gluten-free diet, since my body is no longer so used to it. But, I'm working hard to eliminate that damn gluten as completely as possible.
if i do develop problems with soy, i would do my best to stay vegan, and in a worse-case scenario eat low-level bivalve invertebrates, which to me is better ethically (and probably health-wise) than dairy. I'm very much hoping to avoid that, i do love my tofu and edamame.
Of course, everyone's body is different and I don't mean to imply that those that struggle with the dietary limitations wrong or weak... This is just my take on things...
Best of luck to you.