We have no idea who started this myth, but just like her sexual appetite, her preference for kinkier pursuits (from kinda vanilla to You want me to do what?) is not contingent upon the absence of a Y chromosome. Some men are all-missionary all the time, some have as many fetishes as freckles. The same is true of women.
With this in mind, you should definitely share what you're into. Unless you've only been dating for a few weeks, or what you're suggesting is illegal, there is absolutely no reason why you should not express even your most eyebrow-raising preferences.
Chances are, she's more open-minded than you think, and if you mention it in conversation (before you get in bed), she just may surprise you by not only obliging your desires, but sharing her own!