I can only speak about my own experience. I rely on Mestinon (90 mg. every 3 hours) and coffee.

Coffee seems to give me a boost in the afternoons, just enough to get done what I need to. I can't do immunotherapy. I have not tried IVIG but would like to (long story).
For me, it's about managing with activity alternating with rest. It's depressing as H@!! but it's what my life is. There are signs that I am getting worse as of late but it's so hard to say what will happen in your case.
It would probably be better if others who have experience with those drugs comment on it.
I'm sorry you don't have insurance. I wish they would've tried for some kind of public option but most people don't understand the trade off of that with "spending."
Annie