This is very interesting to read, as I had the same experience: there was a time when absolutely everything on the allowed foods list gave me massive bloating. It was so depressing because I was doing my best to get better and seemed to only be getting worse.
I don’t know if your nutritionist meant to rip you off as such. It is possible of course. But it is also possible that they just jumped into a diagnosis they could think of, in not knowing what else to do. Maybe they even really meant to help you, just got it all wrong. I kind of ended up doing this to myself: was so convinced that I had Candida that I was too busy obsessing over doing the treatment right to notice that it wasn’t actually working. Until I had to confront myself because doing the same thing over and over and expecting a different result surely is a sign of insanity!
(I don’t qualify to get the buckwheat because I am not in the UK so can’t help with that.)