"Casual"

??

https://www.youtube.com/watch?v=i32aVNk78OA, it's this lol. I thought it was funny to share, lol.

No, I don't think you're being silly thinking that being casual can turn serious. You never know what might happen. Make a little bit of effort but don't go overboard.
(Funny, my school is going on a China trip in 2 weeks just like her.)

Being away for a possible 3 weeks is hardly a reason not to commit. A few months would bother many people. A year would bother most - but lots of people do LDR's. She's not that into you, don't go into it if you'll just be desperately hoping it'll turn serious - there's a slim chance it could but likelihood is it won't.
P.s. Casual can mean whatever really, meet however much it feels right. It just means not exclusive and no commitment.

Lol you never know, could be the same trip! So should I continue seeing her on "dates" or just invite her round?

Surely 3 weeks is enough to think to yourself that you don't want to commit right at this stage? I was just thinking that she could possibly(hopefully) reevaluate the situation after the 3 weeks?