I understand all too well about loss, and family ties.
I can appreciate the situation with your sister, it is not easy
My twin sister was killed when we were five years old. My Father passed in '68 when I was 3 months into VN, I was 20. My Mother was gone nine years ago. And my 3 year younger brother, barely two years ago.
That was all of my family.
In my three consecutive years in VN, (yes 3 consecutive, I did not come home for 3 years) I was with a Ranger Co attached to the First Infantry Div., we were LRRP's, it started out with 83 men, at one point we were down to 41. That was a lot of brothers to lose.
You must stay as close to your sister as much as you can and be there for support, that is all you CAN do for now. There is an awful lot I would have done differently but I have little regret for choices that I made. Above everything, Family needs to come first. Cherish the time you do have with your sister and with the rest of what Family you have. Take the time to be with them as much as possible.
Just my two-cents worth of advice.
Concentrate on the now, and if later you choose to move from there it will happen.
Ken
RLTW