You have IBS, yet you eat veg and fruit?
Big no no.
The fresh fish, chicken (and other fresh meats) are good, but any high fodmap foods, ie. prebiotic foods (which feed bacteria, fine if your gut bacteria is balanced, not when it isn't) will only inflame matters.
Do you get bloating/belching?
If so, that's due to the bacterial overgrowth being fertilized by the veg/fruits, which produces gas, thus bloating/belching, and your gut never heals.
In your shoes I'd cease with the veg/fruits until you get your gut health back, stick with your meats, and add brown rice with the meals. Take no other foods or drinks. For fibre, and this is the crucial part, psyllium husk powder, start with one level teaspoon in 350ml of warm water per day. Build up to a max two teaspoons per day (1 teaspoon per glass).
You starve the bacteria, allow your gut to heal, and psyllium as the best fibre (gastroenterologists go to it first) will sweep away the waste.
Adding a probiotic supplement (a pill, not foods such as kefir, yogurt etc as they will only aggravate IBS) is a decent option.
You mention autoimmune issues, do you have joint pain? Your gut is circa 80% of your immune system. Fix that, and you go a long way to alleviating autoimmune problems. Exercise, which you do, is good in that it's a natural immunosuppressant as it lessens the body's immune response, and anyone with an autoimmune issue the immune system is working too hard.