What you’re living through sounds like my idea of hell. And I’ve been there briefly. I went on this fasting mimicking diet a couple times and I noticed that afterwards I would gain back any of the weight that I lost immediately unless I ate like only 700 or 800 cal a day but of course I felt like shit doing that. A conclusion I came to is that I need to eat a normal around of calories for a few months and then very slowly start to ratchet the number of calories down. Also I try to make sure I eat more protein than carbs, and that a lot of my carbs are coming from vegetables and not processed food. But I track my calories in my exercise religiously and I will probably be doing that the rest of my life.

I think healthy weight loss looks different for each person so my approach may not work for you, but you are obviously not happy or satiated now so I strongly urge you to keep looking for a solution.