Shes in High school I'm in college, 2 years between us. I like her, but I'm not sure if she likes me

I recently graduated, and I went on a retreat as a leader. My sister who is 2 years younger came along with several of her friends, apart from them there were many other people who came from different schools and we didn't know. On the bus ride there I got into a conversation with 3 of her friends, and they were pretty cool. I'd never met these particular friends before, so it was good to get to know them. One in particular stood out, I can't really explain how but she just did. When we got to the retreat ( which was 3 days) We didn't talk as much but this one always seemed to try to be near me. Being a leader I often came into the room late when everybody else was gathered, and at least 3 times the only seat available was beside this girl. It could be coincidence but it was always the same chair and similar circumstances. Here Ill say that I do find this girl attractive, and I do like her.

On the second day a bunch of people started a massage circle, I ended up massaging her back, when most of the rest of the people had gone we were the last 4 people participating. She could have left at any time, but she didn't. I'm not a controlling or dominant guy, so I doubt she felt intimidated.

Finally on the bus ride back, I had got on the bus first and had no one sitting beside me. I was near the back and there were no double seats left in that are though there were some in the font. she got onto the bus with a friend and instead of sitting with her up front, she went to the back and sat beside me. We got to talk some more, but not about anything serious, just the usual career/university stuff. we talked about 45 minutes on a 1 and a half hour bus ride, the rest of the time we talked to people around us, or just sat in silence. We were sitting pretty close, our legs and sides were touching and she never moved away, or sat somewhere else. That was about the extent of our contact.

Now the retreat is over and I have this weird feeling whenever I think of her, its like a sense of loss. Now I'm 18 and graduated, shes in grade 11 and still has a year and a half of schooling to get through. Shes also a friend of my sisters, not a BFF or anything but still a friend. I wouldn't mind getting into a relationship with her but I have no idea how to do so, or even if this is a good idea, due to our age difference and her friendship with my sister.

Whats your analysis of this, what should I do?

Sounds like she's interested.

Two years difference isn't that bad for a dating relationship if her parents don't object. See if your sister has her email and try to communicate with her. I wouldn't rush into anything intense. At your ages, both of you have a lot of time to see where you fit in. Take advandage of that time and get to know her.