Unsure of where to go from here

Buddy of mine introduced to me (24) this girl (19) a couple of weeks ago and we decided to all go out one night. Me and this girl hit it off pretty well and ended up hooking up that night. She was a great lay, and now I really want more, but things have gotten confusing.
The first time i asked her out, she cancelled the same day as out date, but had a legitimate excuse (family issues). I let it go, and didnt talk to her for a couple of days. She tried contacting me and i told her i was busy. She ended up texting me "I miss you". I took this as a great sign, and asked her out again for the following weekend, and once again, she cancelled at the last minute. WTF.
I decided to just let it go again, and not contact her until she contacts me first. But its been a week now and still no word. Has she just lost interest? Is she playing hard to get herself? What should i do?

She sounds like a Flake. Maybe she is also seeing someone else. I think that you have waited long enough to give it one mores shot. I would try to plan a group thing like when you met her last time.

Was not contacting for a week as a form of punishment for blowing me off the second time a good call? Or does it show i care too much? And how should I go about reestablishing contact with her?

I dont deal with younger women just for that reason. Most 19-22 yr olds are immature and still dont know what they want out of life. Dont get one-itus, but if you wanna see her again plan a group event with the same friends you met her with as mentioned before. I'd personally move on though.

I agree with Ziploc. I had a similar situation with a girl once except she cancelled about 5 times but kept asking to reschedule. I just ended up dating another girl and when we finally had a catch up i told her i was with someone and some of the cool things dates we had organised. Since she had left it so long she was just in 'friendsville' after all. 6 months later she sent a txt telling me she wished she hadn't cancelled so much and asked me to leave my then girlfriend.

Dude don't bother. Don't contact her. If you really want to maybe salvage a situation do as Ziploc said and organise a ground night out. Girls love having a laugh esp in a group environment and a few well placed wingmen can change things easily. Just need to make sure the wingmen don't take the spot light but actually back you up.