Hi Eli,
This is very common. While I do not have personal experience with an
ED, I have had IBS since I was 6 so I completely understand everything you're saying about "safe foods."
One of the main things that is impacted by any sort of dysfunction of our gut is the microbiome, which is why probiotics are such a common recommendation. If you aren't already doing so, they are a very safe, effective, over-the-counter supplement that many people find beneficial. You can ask the pharmacist at your local drug store for a recommendation on brand/type. Alternatively, you can add more pro/pre-biotic foods to your diet so fermented foods like kimchi, sourdough, and kombucha, but also oats, bananas, berries, legumes/beans/peas, garlic, yogurt/kefir.
You may want to also pay attention to the foods that end up triggering you, so keep a "diet diary" and see if you're just reacting to the same or similar foods over time. Many people with
ED-related gut issues end up with IBS or IBS-like conditions and seeing if you're reacting to common triggers can be helpful. There are classifications of common triggers for IBS called FODMAPs but especially as someone with a history of EDs, I would not recommend going down that road without the support of a dietician/PCP - for now just seeing of you react to the same/similar types of foods may be beneficial.
Those things aside, I think you need to be careful of many of the other common "remedies" for gut-related issues as many involve dietary changes that may be triggering for you and should only be done with the support of your healthcare team.
Oh, and LOTS of water.