<human>: Can you succinctly summarize the text in 1-3 sentences?

Hey guys. I [18M] met this girl [18F] at an event for incoming first year students. To make a long story short I got her number, we went out on one date a week ago which I think went pretty well (although it only ended in a hug which is fine I guess because I had only known her for a few days). We started texting/calling back and forth and she seemed into me (long thoughtful responses, exclamation marks, the odd emoji). I asked her out on a second date a week ago and she said yes. The date was set to be today, the day after our second freshman meetup so I texted her saying something along the lines of "Aren't I lucky I get to spend two days in a row with you!" to which she responded positively.

Our second date was to be today, the day after another first year meetup. I wasn't particularly flirty with her at the meetup but when I got home I sent her a text saying something along the lines of "I gotta be up early because I'm lucky enough to be spending the afternoon with a special someone! Night!". A short while afterwords she said she couldn't meet up because her sister (who doesn't live with her, she lives alone) grounded her for not finishing her calculus assignments. When I asked her how her sister could ground her if she doesn't live with her she said "she told her everything". I'm not entirely sure if this is bullshit because she is really busy with this course she's taking (she was even doing work at the meetup last night). I said "that's too bad some other time".

Now I'm not really sure what to do. I'm going on vacation tomorrow and likely won't be texting her and she hasn't texted me today. I don't know if I should text her tonight or just give up on her. I'm really not sure why I did wrong because she seemed really into me the night before the meetup. What do I do? Am I pretty much shit out of luck? Why has she suddenly changed her mind?
<bot>: Met a girl, went on first date and had a good time, seemed into me and got a second date but she cancelled with a lame excuse and haven't spoken since. What do I do now?