It's not impossible to get back. I had this exact problem for ten years, and I suffered from an eating disorder, and when I got therapy one of the most useful tools I got was an app called Recovery Road. You can use it for free even without a therapist. It retrains you to become mindful and intuitive about how you eat. When I started I couldn't even recognise hunger and fullness cues because I'd become so detached from my body and so everything was done with calorie counting. Now I am an intuitive eater and my weight (not that it matters) is almost exactly the same as it was before I stopped restricting. I would guess your set point weight is very similar to what you are now.

Give Recovery Road a try.