Middle Sis, you said it all when you said "I can't believe I survived it", I feel the same way. But we really didn't have a choice in any of it. I know that I was always under the assumption that I would have my brother and sister around until we were all "old and gray". It's hard having lost my parents, brother and sister.
Lisa, I am so sorry that you have lost so much at such a young age. I know that it must make your grief much harder to deal with. I wasn't nearly as young as you are when my losses began. Even though my friends were very kind and supportive, they just didn't have a clue to what I was really going through. Our lives change so dramatically after one loss, much less multiple losses.
Take care