You'll get a lot of people along on here telling you to count calories and have willpower and try various diets etc. It sounds like you already have, and it hasn't worked.
There's only so much you can do, OP.
Obviously, the best way to lose weight is through diet and exercise - you know that - and if there is any way whatsoever that you can do it that way, it will be much better for you and your health. A gastric sleeve isn't an easy way out, it's major surgery. My friend had one a few months ago and although she is doing well, it was a big deal. She had to be on a liquid diet for a long time.
So if there is anything you can think of that you haven't tried, try that first. Have you had a personal trainer? That is what worked for me. (The friendly supportive type who has experience with overweight people with injuries etc - not the shouty type!)
Sometimes you need external motivation - a life coach, a nutritionist, a trainer, a counsellor. It seems expensive but you will spend a lot of money on a gastric sleeve, so it's worth looking into thse sources of support if you haven't tried them. You need someone who understands your situation including the mental health side and potential ADHD.
I really, really would encourage you to do all of this before going for the gastric sleeve.
But if you have done all of that, given it a year or two (it takes time), and still haven't shifted any weight, then I would definitely recommend to start thinking about it. My friend is doing well, her life is completely changed of course, she can't eat anywhere near as much as she used to, but the weight is coming off albeit very slowly. She is very obese but is still only losing half a pound a week, it's still very slow.
Good luck, whatever you decide.