My mother got double vision due to uncontrolled diabetes, drinking too much and smoking - that effected her vision. There can be a few things that effect vision, but MG "seems" to effect it more at the end of the day and is more fatigue driven.
I am sero-negative, that is to say, my blood tests are negative and I am not sure I have it. My EMG came back negative but my SFEMG came back positive.
Did you get a complete check up for all your hormones?