The problem with waiting is that MG is a serious disease if left untreated. Since you have already had what was probably an exacerbation and/or crisis, the chance of you having one again (especially in hotter weather) is great.
Why not call your insurance company? Make it clear that you need to see the MG expert right away. A patient has the right to have timely treatment. And you can see more than one doctor at a time.
The most important thing is to have a firm diagnosis of MG and have some form of treatment soon. You are in charge of your care, not the doctors!
Annie