Sorry that your having a time getting dx'ed.

I'm sorta in the same boat as you. I haven't been dx'ed either but have had some test done. First I had the MG blood test, and it came back borderline. I was then tested again almost a year later and the results were lost.
At the time of blood testing I had the EMG and the SFEMG done. This test wasn't performed properly and the neuro said that she didn't think I had MG but gave me Mestinon anyway. It worked wonders.

The reason that I had to write this is that all the test I had were done wrong. And it really ticks me when the drs then say well the test was negitive so they won't continue to look any further.

So before you have that EMG done make sure that you hang around outside espeacially if its hot out. Make yourself as tired as possiable, exercise, go up stairs if you can.
The muscle that they tested me were the ankle, really dumb since my ankle isn't even weak. Then they EMG my hand, not that weak.

I think the reason that they chose these spots is because they give the muscle a shock, first mild then stronger and I won't lie and say it didn't hurt, becuase it really smarted.
The best test to get if your going to get shocked is the SFEMG. With this test they stick a needle which is attached to a wire into the muscle. If they can stick it into the eye area were your eye is sagging, that might be your best bet.
I've read about these test and it says that, the muscle is to be warmed and exercised.

I hope this helps you and that a dx is in your future, not that MG is great to have, but just having a answer to your problems makes eveyone feel better.
Take care, Patricia