Have you considered Hypochlorhydria (Low stomach acid)?
This is somewhat common in those with dysbiosis and rarely gets mentioned on these forums.
I am a sufferer myself and some of your symptoms are classic Hypochlorhydria.
Bloating, weight loss, gas, etc are typical with low stomach acid.
What does your stool look like?
Betaine HCL (Betaine HCL) is the best for low stomach acid. I still take 8 capsules with every meal.
My stomach and small intestines were likely colonized while my Hypochlorhydria was at its worst. Betaine HCL gave me significant die-off for the first few weeks so I had to start slow (1-2 capsules with meal). I can now take 8 capsules with no die-off and amazing digestion.