Hi Rach,
Gosh - you've really been put through it! Crazy how they can give and take away diagnoses! I can't really be of too much help but wanted to let you know you aren't alone. I can SO empathise about the elephant being parked on your chest (great expression by the way) and the annoyance at your limitations. Everything sounds like MG to me, but what do I know.... when I was diagnosed my neuro said my symptoms were so mild I'd only ever need mestinon - a year later and I couldn't brush my hair or dress myself. Hope you are okay and keep your spirits up!
~Kathy