How quickly do symptoms set in? And safe foods?

So I do not have a diagnosis yet, this is the main condition my doctors are considering.

I have the classic warning symptoms where I'm full after two bites, nauseated and in pain after everything, but anything with fat and fiber can give me unbearable symptoms. They are thinking I potentially have an intermittent version where sometimes ill barley have symptoms and other times I go into severe flare ups, (currently in a very bad episode).

But I'm wondering how soon after eating the symptoms kick in for other people?

For me its pretty much immediately, which makes it really difficult to even close to meet my nutrition need, as I eat two bites and I'm already suffering.

So far I'm pretty much on a mainly jello, broth, and powerade diet. I can tolerate little amounts of rice and seaweed, as well as the occasional gummy from a fruit snack pack, and if I wanna deal with a bit more pain I can eat a little bit of a scrambled egg. But thats all I've found so far. (Doesn't help i have 8 million allergies, including being gluten free, due to mcas, but other food recommendations would be great!)

But yeah, just wondering if other people experience immediate symptoms, or if this is abnormal?