OP, having read the whole thread, I'd firstly like to congratulate you on wanting to change, which is the biggest and most crucial step.
Full disclosure - I don't have any real experience of overweight, but I do have experience of coaching and mentoring, and hopefully my post can be of some use to you.
From your posts, you sound like a deeply thoughtful and intelligent individual, and I feel approaching your issues in a slightly less binary 'must lose weight = no food' way may be of use to you.
From my perspective, I am both incredibly competitive and a natural systemizer, and when I have something challenging to do, I find almost planning it like a project helps me enormously.
Have you heard of SMART goal setting? This helps you break your goals (in your instance, weight loss and re-educating your palate and appetite) into achievable chunks - so, rather than think 'I have to lose 13.5' by X or I'm a bad person', you reframe it as 'I will change my breakfast habits to X for X weeks. This will assist me in losing Xlbs and I will feel better and more energetic'.
It is one very small goal, but undertaking it will help you establish better habits and ultimately reach your long-term goal. A journey of a thousand miles starts with one small step!
There are lots of resources online about SMART and how to apply it personally as well as professionally - you may also find journalling helps.
I also think you would also enjoy learning more about food and nutrition from an objective, rational PoV - I recently went down a bit of a rabbit hole learning about ancient grains such as freekeh, and brought my new knowledge into my cooking (in addition, your palate changes as you get older and, as you are only in your early 20s, it won't take long to re-educate it!).
Now, clearly there are reasons why your bodyweight is at is at a relatively young age, and I'm not going to pry, because it's none of my business, but I do also feel that therapy may help you, particularly person-centred therapy. Getting on the NHS bariatric pathway - even if you don't go for surgery - will help you access this.
I genuinely believe if you challenge your brain, rather than your body, you will see rewards relatively quickly.
All the very best of luck to you.