What do i do now with this girl i feel stuck?

ok so this sunday the girl i like called me and told me that she liked me back, and that she wanted to hang out this weekend. i'm leaving for washington dc this weekend and can't hang out. we decided to hang out on thursday and go to the beach. It was gonna be a double date but the other guy bailed at the last second, so we ended up hanging out with two of her friends. The entire time i didn't know what to say because they were all going back and forth with inside jokes that I didn't know about. I texted her afterwards to see how it went, and she was giving me the one word treatment, and the conversation just fizzled out. I'm about to get on the plane to washington, and I'm not sure what to do I really like this girl and i don't want to give up. your thoughts?What do i do now with this girl i feel stuck?
Enjoy your weekend in DC. Ask her out for a one-on-one date when you get back and see how that goes...