Some of those symptoms are common for MG. Some of them don't seem so common (metallic taste) but this disease has all sorts of shapes and sizes. If you respond well to mestinon that's great because it doesn't help everyone. MG or not, perhaps just being helpful is a reason to take it.

One thing you didn't mention is that MG is especially visible with repeated muscle movement. Has anyone tried to measure your fatigue response to repeated muscle motion (over say a 5-7 minute period)? The SFEMG test does that with an instrument but the neuro docs often try to measure muscle fatigue 'manually' by asking you to move the affected area to look for fatigue buildup.

Another test to try when ptosis is flaring is to put an icecube on your 'bad' eyelid to see if the ptosis reduces or disappears. All of that is good but you really need to see a neuro doc that knows how to diagnose MG. MG is not so common and even trained neuros seem to get it wrong sometimes. Good luck. I hope you have easy answers soon.