Huge crush on this girl. What should i do?

There's this girl who has given me rather confusing signals. She's stunningly pretty, had this nervous way of talking that makes me want to hold her and plant a kiss. I was helping her with career advice in grad school and she had mentioned that she has a BF in another city in ping. The first time I met her (on her request), she was in scrubby clothes -- would a girl who's interested ever show up in scrubby clothes the first time? Yet, the next few times she appeared dressed up, asked me to dinner, we flirted heavily, but she gave mixed signals rest of the night. She's also gotten me a postcard from her vacation, rubbed up on the dance floor with me and said "I'd like to get to know you". At the same time, she's also ignored my dinner request once, brings up her BF when I respond to her flirtation. She gets pissed when I dance with other girls and if I don't call her. Yet, she hasn't truly talked to me in depth to get to know me. What would you do?