That sounds like a really good plan! My only concern is creeping her out by messaging her on Facebook. I wouldn't want her to think "I've only talked to this guy once, why does he keep trying to talk to me?" The last time i have facebook chatted her was about a week ago and it was a really short conversation. I didn't think it went well, but my friends said at least she responded instead of ignoring me
Today was our last final exam unfortunately. So I don't think i will be able to see her at all before next year. Should i just go on with your suggestion then and messaged her at a later time?