I'm sorry, Pizza. I just prayed for you, your sister, and the rest of the family. I've read in some books for Christians that a Christian's life is the story of God's work in yet another human being's life. Pain is sometimes a big part of God's work in our lives, and it seems that Christians often suffer more than non-believers (I stole this observation from CS Lewis, btw).
Anyway...because of Christ, there's meaning and beauty and depth to suffering and pain, for Christians. Easy for me to say, I know, but...I believe it to be true, which is why I'm writing this.
Some people are weaker, more fragile, more vulnerable than others. Your sister is an example of one of these people. Christ is with the least of these in ways that...defy belief, defy understanding. I say this as someone who deals with a psychotic disorder (w/ meds, clearly) and all the stigma and everything that goes with it. I don't quite get your sisters' sort of pain, but I do, to a point, "get" being amongst the least of these, dependent on others, all that.
Anyway...God is good (all the time), and His work has meaning even when it also proves frustrating and downright depressing. CS Lewis wrote something to the effect that "Pain is God's megaphone," and I sometimes think he's correct.
Rambling...I don't have a whole lot to share with you, just that I'm praying and that God's work in your life and your sister's life has some kind of depth and meaning and purpose, even if the rest of the world doesn't see it or "get it."
You're in my prayers....