I'm not a doctor, but I believe that MG does not present with oligoclonal bands or brain lesions. That sounds like MS. The ACHR antibodies certainly point to MG. It could be you have both conditions. You need a good neurologist who can help you through this. Are you in a big city with excellent specialists?

I hope that you are able to find a doc who can help you with this quickly. I can sympathize with you. The unanswered questions are so frustrating.
Keep us posted on how it goes.