If you didn't get a def answer well then I would say that she is thinking about it for sure.... have you played with her there ? Talked about your fantasies and hers ? Be open and honest and she will be too... thats the only way that you can completely have a satisfying and enjoyable sex... I for one luv anal... I was open and told my guy that I want to be tied to a saw horse soon and he can do whatever he wants to me... hoping for a bit of slapping around and of course anal.... YUMMY
You can't get her to do it unless she wants to. Talk to her about it, bring up some good points but in the end if she doesn't want to then there is nothing you can do.