Well, how old are you both? Maybe she is just scared you don't want her for more than sex. Have you, uh, cough, cough, I am going to get grilled here for this, but....sent her flowers? Or something sweet like that? Called her just to say hi? Try being more up front. Explain all this to her, the same work thingy, and if you are still into her, and you sound like you are, go for it. Just tell her, she sounds too scared to try for it on her own. And maybe you always talk sex because you two are like steaming for each other!!!
Good luck! And, don't believe a word anyone else says, women LOVE flowers. I've seen them go nuts getting them at work, but if you can't do that, send them to her home. It's very sweet. Even I get a thrill when my co-workers get flowers and the four times (yes, I remember each time!) I got them? Oh, my! It was wonderful!
But, just mho