I am sorry you have this dilemma. Eating can be tricky with IBS.
I tried the Low Fodmap diet foods, and did the full 8 week elmination and then re-introduction phase. But while trying low Fodmap foods I found out very quickly that some didn't suit me personally, at all.
If my tummy is going through a really bad phase, I eat extremely plain simple foods for a few days and that will often help settle things down. I have IBS-D, so my ideas may not be okay for you if you have IBS-C.
Foods that can help to calm my tummy down are: plain boiled white basmati rice, plain steamed (or baked) white fish (not an oily fish) , toasted white bread (I like Italian ciabatta toasted) I am okay with a little butter on it but some people with IBS wouldn't be ok with that.
I also eat well cooked eggs, and usually just boil them.
If you eat meat, then some plain baked or boiled chicken just cooked in a little water, but well cooked might be okay for you too.
I can also handle just a little bit of steamed spinach or a few fine green beans, but again those veggies might not suit you.
The secret for me is keeping everything super plain, and only adding salt as a seasoning. No other seasonings. After a day or two my gut will calm down, and then over the next few days I slowly introduce very small amounts of my usual vegetables, and try small amounts of other foods to see how things are improving. If there's any upset, I go back to the plain foods for a while, and try again when I am steadier.
I also take a multivitamin/mineral tablet each day and a B complex just to make sure I don't get deficiencies, as even though they'll steady my gut, the plain foods won't have enough nutrients. But if you do that, choose a tablet which doesn't have any additives that you are sensitive to.