I suggest watching the videos from Dr Berg, there’s a lot of good recommendations for healing and IF best practices on his channel.
https://youtube.com/c/DrEricBergDC
Usually the videos are short and on point.
Gerson Therapy. It takes effort but works.
Eating disorder in the past as well but do 7 day fasts eat a week of vegan and do another 7 day fast followed by 4 days of clean eating with a few days of real life eating.
I get the not wanting to go too far but listen to your body! Get mental help to harness that monkey mind.
I have CFS and POTS also. I find that I respond to eating less much like you do. I’m currently doing 16+ hr fasts; I feel best at 18-20 hrs. I also find that lower carb is better for me. I recently tried erythritol and that seems to curb my sweets cravings. I also feel oddly better when I eat it.
I started out just adding a couple of hours between last/first meal until I hit 16. After that adjustment, getting to more has been fairly easy for me. Feeling better makes it easier to follow also.
I mainly eat whole fresh foods. I don’t mind repetition so I tend to eat some variation of the same thing.
For me, just keeping on trying it is what works. I’ll try some other things now and again and it may throw me off. I just work at getting back to what I know works and avoid what has not worked for me.
I wish you the best. You are your own best help with these conditions, in my opinion. You have to do what works for you.