Hi, Comeonthen,
Here's something about myasthenia gravis:
Myasthenia Gravis Fact Sheet | National Institute of Neurological Disorders and Stroke
Since you've consulted several doctors and had no clear diagnosis, maybe you'd be more at ease if you just coasted along for a while, doing whatever you can to help to ease your symptoms. You may find ways of working around some of them.
And keep a log of your symptoms, along with a record of any infections or trauma. After a year or two you might want to go back to your search for a diagnosis by seeing more doctors, or returning to previous doctors.
Myasthenia gravis and MS are both difficult to diagnose. Often a person goes for years before being diagnosed definitely, and even then there are errors. I know this isn't encouraging, and I'm not saying you probably have one or the other. It's possible that you have some other problem entirely. But I do think it might be time to stop looking for a diagnosis unless you find you're no longer able to function at the level you need to.