I think many people who are diagnosed with Celiac disease also struggle with corn and oats, even gluten free ones.
Take yourself back to when you were feeling wonderful and eating low carb. This will have been largely sugar free without corn and oats as well. I also suspect that the additional substances added to gluten free alternatives taste the same as traditional options and have the same texture are slightly problematic for some. (Guar gum, xantum gum, syrups, dextrose, all sugar derivatives).
We have complicated dietary requirements and have a functional medical doctor where we live and he has suggested it is best for us to avoid most grains (we eat rice), limited nightshades (tomatoes, potatoes, aubergines, peppers), no sugar (and limited fruit), no yeasts or fermented foods, we also avoid dairy, beef, lamb and any beans, peas, chick peas etc. It is really tough but I feel better on it. I will be back on it today as I have been gaining weight, feeling the emotional side effects and feeling very tired.
So, if I were you... I would keep it simple. Quinoa cooked in coconut milk with berries for breakfast or eggs, avocado, chicken. Then for lunch, I have soup with seed crackers (ground seeds mixed with butternut squash and then baked.) And for dinner, rice, sweet potato, rocket and salmon.
It's almost the same every day but I do feel better. Less pain, calmer mind and more energy.