Have you looked into Biotin? IME it was the single vitamin to require more bicarbonate production from the pancreas (not measured, just by symptoms).I have noticed that my blood pH is completely normal in the fasted state:
In my case I suspect some block of biotinidase (I took accutane in the past and it does block biotinidase preventing one to extract biotin from food) and I had some signs of excess acidity (bursitis, teeth demineralization, non celiac gluten sensitivity, ETA smelly sweat, hair loss).
Biotin is said to be mostly produced by gut flora and you could have excess production? In that case B5 would be the antidote since it competes with Biotin for transporters/receptors.
(Does it make sense to you @Lolinda ?)
I know my wild theories aren't very popular since I base them on my reading of basic metabolism + personal experiences, but this could be one underlying factor since it is tightly related with food intake for you.