Haven't read all of it but I do get you, OP.
One thing I'd say is avoid dating sites. They're horrible and can be very demoralising though of course some people like them and do well, but to me it didn't feel natural or fun, it felt really embarrassing and I never felt sure enough about anyone to meet them in person.
Someone IRL would be much much better so you could gauge the attraction and what they were like, much more easily.
People always said to me go to an evening class, do something you love doing, you'll meet someone.
Well I did - I got myself back into something I had given up when I had ds2, and suddenly I was meeting loads of blokes all the time and being asked out etc.
It was a huge confidence boost and all it was was having something I was into and passionate about - because then people who share that passion notice you.
I'm now with someone fantastic after a long spell alone. I am still not sure how it happened but it is real and I'm not dreaming - so I want you to know you still can do it, too.
Good luck and chin up. I know how desperate it can get and there is only so much 'pretending to be fine on your own' you can manage.
But bide your time, and get out there
If I'm loveable with all my terrible faults and failings I'm sure you are too.