Have you ever looked into the low-FODMAP diet for IBS? I was just reading about it again and it sounds as if it helps a lot of people.

A Beginner's Guide to the Low-FODMAP Diet-from Healthline

I'm not at all fond of the word "diet" because for me it seems restrictive and I would become all consumed by it in a somewhat obsessive way as I can do from time to time. .

It is more difficult following a low-FODMAP diet when you are vegetarian but it can be done by switching out the large amount of meats for other types of protein. You just have to make sure you're getting that protein. Wondering if you have a blender?

You can still eat lentils but you need to make sure you cook them properly. Soaking, draining, cooking, straining well.

btw I'm a vegetarian so I understand not eating meat and how I had to totally change the way I shopped and cooked to make sure I get enough of everything I need.

[mrsD used to post about low Fodmap a lot so there are many old threads on the forums if you want to ever search]

Added later - Foods high in FODMAPs - Healthline