I think she'd appreciate it (or if not now, she will) if you gave her a big hug and told her how much you'll miss her. I'm on the other side of your situation. My sister (she's 16) has basically become the only child. My twin brother still lives at home, but he works and goes to school full time.

It'll take time to adjust to the new home environment, but once you get in a routine it'll be easier. I'm not sure how close you and your sister are, but this actually might be good for your relationship.

I never really had much of a relationship with my sister growing up. She's 5 years younger than me and we never had much in common. When I left for college 3 years ago I was SO happy to be leaving my parent's house. Now, I miss my family more than ever. I talk to my Mom or Dad every day on the phone, and often call to talk to my sister. We've had the best relationship that we've ever had. I do get all nostalgic from time to time, wishing things could be like they used to.

I know you'll miss her and it'll be hard to get used to. You're right, things won't ever be the same again. But it doesn't mean that you shouldn't make the most of it.