Ladies Help!! PLEASE?

Okay so i've been talking to this girl for about 3weeks now!! she got a bf, but there's something about her, I mean she's beautiful!!! so she came to see me at work last week, but that's old news!!!!! OKAY i texted her the day before yesterday, but didn't text back. so yesterday, we're in class, and I didn't even look at her for the first hour. I see her looking at me from the corner of my eye. and I finally look at her and smile, she smiles back. DO YOU THINK THAT WAS SMART??? we were supposed to get something to eat today during our break, but she said she has work to do, and said we got to postpone it, i'm like okay. kool!!! but it felt like she blew me off!! WHY??? Theres just something different. you think she's over me, or not feeling me?? I waved to her in class today, and even when we were leaving, I said bye,usally i would wait for her, but didn't .WHAT SHOULD I DO NEXT?? TEXT HER, HELP HELP HELP