Hi KirraJade
Welcome to NeuroTalk

.
I have read what you have shared carefully and these are just my thoughts - your new GP sounds good to me.
"
He referred me to an endo"
Good plan.
"
My Ana is 1/2560 [...] AChR antibody"
That ANA titre sounds very high to me. Maybe get your GP to refer you to a clinical immunologist who will be able to do more detailed testing and then (depending, and after talking with your GP) refer you to a specialist rheumatologist and/or neurologist.
All the best.