Well your well on your way to banging this chick but of course she was going to flake on you after you gave her YOUR number. Try not to give a girl your number, unless she askes for it of course. Get HER number instead that way YOU are leading this "relationship" playa. She clearly is attracted to you, you've received the IOI's and now its all about building comfort and closing. Get her number, if don't already have it, and take her out whether it be the club, bar, etc.
You might want to do this in a group as it will seem non-threatening to her. Isolate her and then seal the deal. Once this happens just watch how fun your workplace becomes then
