I don't know what to do, difficult situation

Long story short: I've had a crush on this girl since high school. I got out of a long-term relationship 6 months ago, she got out a few months ago. Even when I was with my ex I was still shy/nervous around this girl - I've never liked anyone else as long.

We go to colleges on different continents. I was home for Christmas, and we were at the same NYE party, and made out for the first time, and spent a good hour together, alone.

Problems:

1) She spent most of NYE with me, dancing, kissing, and we parted ways at the end of the night. I don't know if it was because of the holiday mood or the alcohol or her liking me or maybe her rebounding.
2) We talk regularly on MSN, but we always have. She's been slightly more flirty since we kissed.
3) I asked her out for coffee when I was in town the day before she left for school again, but she canceled on me because something came up at the last minute.
4) I don't know if I should just put myself out there. I don't want to ruin the friendship. But I also don't want her to get back with her ex, since they're always on and off. I'll be home for good in May.

Questions:

1) Should I send her flowers for her birthday which is coming up soon, or Valentine's Day? Maybe anonymously and say she has a secret admirer?
2) Should I just leave this alone until I get back?

I hate this situation. I feel like a barely pubescent boy who can't stop thinking about his crush. This *never* happens to me.