Let me throw out this possibility. Is it possible that she was being less than honest with the other guy (and perhaps with herself.) Is it possible that she was younger and less secure in herself (and in that relationship) than she is now in this relationship. She might have been putting out a raunchy affect, not because she was that way, but because she thought that was what that fellow wanted. Her experiences have shown her what she likes and doesn't like and where she wants her boundaries. Experience has also given her the confidence to be honest with you about that. It's also possible that her boundaries have moved, for what ever reason. Not because of you, but because her boundaries are different than they were in the past.
Is it possible that she wants to have a relationship with you that doesn't revolve around sex? Like, maybe she really likes you and wants to make sweet romantic love to you in a spontaneous way. Maybe she's sick of calculating how fucking cool she'll be if she gets fucked in the ass and genuinely wants you to like her. smfh .
What I would do if I was in your position would be to tell her some of my sexual fantasies or fetishes that we haven't tried yet and then ask her if she has any she would like to share with you. Might get the ball rolling.
Is she a lot older than she was when she had that convo with the other guys? May be she has matured and realized that she’s not into that as much and was just trying to make it seem like she was to get attention from the wrong guy. May be she respects you a lot more than the other guys she NOT with and doesn’t like the feeling of being that person with you. May be you two have something way more special and have an emotional connection she didn’t get with the other guys. And because of that you satisfy her needs completely without her having to verbally tell you. You won’t ever know unless you ask her. I find it easier to ask specific and gentle questions with a calm low voice when discussing a touchy subject. Hope this helps!