I have/had terrible terrible IBS.
I had particular difficulty pinning mine down because it was both caused by terrible stress and also by a very small number of FODMAP foods so FODMAP didn't fix it if I was stressed, and almost everything was fine if I wasn't stressed.
What did I do? I left my job and got a new one with an organisation that values me as a human. I'm still regularly super stressed by work but it doesn't impact me at all in the same way as it did in an organisation where I had no value except as a cog in a machine. My current organisation recognises my contributions as valuable and views my humanity as a benefit with consequential human things like illness that come with it - my previous job would have far preferred to employ a robot if a suitable one were available.
I know you've mentioned diet but I would consider rethinking it - I thought for absolutely ages that mine wasn't diet related as I looked at the lists of different FODMAPs and was fine with lactose, fine with gluten, fine with frustose etc etc. Then I spotted a little group called galacto-oligosaccharides (sp?) for which everything listed was also in another group of FODMAPs pretty much so I had dismissed it as being a problem - but it was things like e.g. soy, lentils and beans. They can all make me unwell enough I can't go to work and keeping them cut out my life entirely is (as long as I don't go vegan/vegetarian) a very easy and worthwhile sacrifice.
That plus then a raft of medication options: omeprazole for stomach acid (symptom nausea generally), mebeverine for churning, simethicone for wind and loperimide for if everything is going wrong, plus a radar key off Amazon, means I live a basically normal life now.
To start with I had to take at least 2 medications absolutely religiously, it was frustrating and annoying but it got me to a point of stability and now I just take as and when required (less than once a week).
I recognise not everyone gets as good a result as that, but I lost 2.5 stone in 10 weeks when first diagnosed, sitting crying with pain while I worked, having to leave the room to be sick with the nausea and when a doctor told me my life might never improve I genuinely wouldn't have minded if I had never woken up again. It took 3 years to get to a point of semi stability, a further 3 and the acceptance that I needed to leave my job to stabilise it properly and I've now been reasonably fine for another 3.
Sorry about the total essay!
PS @Yogateacherherehello I would also love the link if you didn't mind!