Hi Barbara, I hope that you are getting some rest and taking care of yourself. If you don't take care of you, you cannot take care of your sister.
You have quite the dilemma brewing, travelling the distance to get back to "home sweet home". It might be beneficial to weigh advantages and disadvantages to travelling this distance. The one disadvantage I can see is the one you pointed out, 7 1/2 hours of travel time. Second, more and frequent hospitalizations. Advantages, she is getting the best/adequate care. You have seen to that. However, you may be forced into a decision sooner than you think. Prepare yourself, you can do this.
Have you ever thought about
local placement near the hospital, where she could get the care needed and not have to travel that amount of time with each hospitalization? This is a question that you may be approached with. Have you discussed or asked your sister what she wants, feels or thinks? It seems that you two have a close relationship and the lines of communication are
open. If you stay one or two steps ahead of this dreaded disease and all of its complications, you may save yourself from a great deal of anxiety.
Someday, I think that we will be able to look back and remember the laughs we shared with our siblings and the fear that accompanied this diagnosis will fade from our minds. You are not alone. You are stronger than you know. Don't be afraid.