College Student in need of relationship help!

Alright, well. I should start from a little while ago during my high school senior year. In August last year I met this girl who, for the sake of this post, I will refer to as "March." March was a junior at that time so she's a grade below me. The second I started talking to this girl, I could tell there was something special about her. We instantly clicked and I fell for her almost immediately. I wouldn't say I was obsessed or anything; I simply recognized that we were extremely compatible. So naturally I developed a little crush on her. Of course she had been dating this one boy on and off for a year so that was an issue.

Seeing how her current relationship status was not changing anytime soon, I decided to go for someone else. I began dating this other girl--very pretty, but turned out to be 100% insane. While in this relationship, I almost ignored March completely. I didn't ignore her on purpose, but because the other girl required all my attention.

We went on a trip with our choir class to New York for a week, where March and I really hit it off for the first time. She was incredibly flirtatious the entire trip and as was I. Honestly, had we both not been taken, I would have made a move right then. We talked very frequently for the next few weeks but it slowly decreased.

May: After dating the second girl for about two months, we split. Oddly enough, March and her boyfriend split on the exact same day but I didn't think much of it. March and I began to talk more often again. Now coming up on the end of the school year, we went to a party at one of my friend's house. I was being very flirtatious this time, commenting on her eyes, joking, playing with her hair, cuddling... you know the drill. So it came as no surprise that she asked me on a date the following week. I said yes of course, but unfortunately for me I didn't see it as a date. Just "hanging out"

It was fun! We were both very much ourselves and the night was filled with laughter. We kept talking for a little while but graduation was imminent and during the summer, everyone kind of grew apart. It was then that I finally realized how much I cared for this girl.

August 4th: I went to a concert with another one of my good girl friends. It was a blast, completely platonic as both of us had other love interests. But over the course of the night we were talking about all sorts of people we knew and she told me that March had the biggest crush on me ever. Being my oblivious male self, I was clueless. And now it just seems so fucking clear and I can't believe I hadn't seen all the signs.

I still talk to March, but it's sort of rare. I mean, I don't expect to talk to her all the time since I'm a busy guy in college and I don't see her every day like I used to. Last weekend, however, I returned to my hometown and went to another party with some old friends, Match included. We talked for quite a while and she was acting flirtatious again: resting her head on me, holding my hand, etc.. So I get the vibe she still digs me but when I text her at all, she seems a bit disinterested. It's only in person when it occurs.

Keep in mind she's not the "flirty type." She doesn't really flirt with anybody else the way she does with me. And she's going to the same college as me next year, so distance will not be an issue at that point.

Don't get me wrong; I know she's not my "last chance" or anything. There are plenty of other girls out there. But I have really never clicked so well with another person in my life. I missed my chance once and I don't want to miss it again.

So my questions are these: do you think I've still got a shot with this girl? What does her on-and-off behavior mean? Should I wait until closer to her graduation day to reduce long-distance problems? Why does she act differently in person than over text or phone? Thanks in advance for any assistance.