I don't know if I can help much. My MG symptoms are so mild compared to yours, but there are a lot of people on this board who can help. I am 75 yrs old, and have had symptoms for about 4-5 years. I have not had my thymus removed, the cat scan showed normal.
I am on 4 x 60 mils of mestinon daily, and my symptons are very mild, with a bit more optical problems than anything else. Before the mestinon, I had trouble chewing--speaking--and raising my arms for very long.
Hopefully the docs can find a solution for you also.
Stay in touch with this group for help. By the way, I was raised in Amarrillo, and spent many years in Lubbock, Texas, until I moved to San Antonio.
Best wishes for a quick solution to your troubles, look to read more from you.
FREDH