Strizzlow20, Panic attacks are no fun and are shouldn't be handled alone! I really do hope you get an expert psychologist or psychiatrist to help you out. They're really invaluable!
It is scary to think about the "what ifs" in life but that same thinking can also make you less fearful. They can make you realize that you ARE strong and resilient, as humans are. And it sounds like you have a good relationship with your girlfriend. People who truly love you don't only stick around when everything is perfect. It's the times that are more challenging that can bring people even closer together.
Have you been to an endocrinologist? Some anxiety states can actually be caused by endocrine problems, like Graves Disease. It might be worth an evaluation.
Have I already asked this . . . have you had your B12 checked?
Are you on any drugs other than the MG ones? I ask because when you get new symptoms (i.e., vision), you should always make sure a drug is not the cause.
You have to know that many illnesses are manageable. They aren't always "fun" but you can live a good life!!!
Perception is very powerful. If you can change your perception about the fear or a disease or whatever, you are then in "charge" of how things will go and how you will feel about them. That's a very important point when dealing with panic attacks or fear or anything in life.
And I think it might be a good idea to be evaluated to see if you have PTSD. Have you had any traumas in life that could have made you more fearful of any future situations? I have PTSD from several traumas (and associated panic attacks). My panic attacks have been reduced to almost nothing, thanks to the help of a great psychologist. There is a new therapy now basically called "touch therapy" that is helping our veterans.
I'm just tossing ideas out there. I hope you'll get someone qualified to talk to about what's going on with you. You deserve to be calm, reassured and happy. Hang in there and know that you'll be okay.

Annie