My understanding is that a regular EMG doesn't usually diagnose myasthenia gravis, but a single-fiber EMG does. I can't tell from your description which one you had. I know that any neurologist can do an EMG, but only certain neurologists who specialize in neuromuscular diseases can do a single-fiber EMG.

Would you consider asking your neurologist to refer you to a specialist? You might have to travel. I got my diagnosis in Boston from a doctor who specializes in MG. My local neuro did two single-fiber EMG's on me and got "borderline" and "slightly abnormal" results and was unwilling to diagnose me. He sent me to the MG doctor in Boston, who did a specialized kind of EMG on my face that involved electrical pulses to make the muscles contract. His findings were strongly positive for MG. After that, my local neuro was willing to treat me.

Abby