Given the fact that she rolls over to show her belly while in your presence when you talk to her is very optimistic! She wants your attention, but her feral instinct to be wary of humans is still overiding her new-found desires, so she has a battle going on within. You have the patience and devotion to allow her to progress at her own pace, and that is imperative. Forcing affections on a cat only makes them retreat even more.

My now Rainbow Bridge Muskrat was once a feral tortie, and in hindsight I think what won her trust was all the time I spent vocalizing to her . . . reading nursery rhymes, softly singing and simply talking to her. The day finally came when she let me put a brush to her, followed later on by my hand, and then as more time elapsed she turned into such a lovey-dovey, lap-cat of a girl! Very rewarding experience.

My advice is to vocalize as much as possible in soothing tones when she is near, and she will approach you when she feels the time is right. You have already layed the groundwork for a trusting relationship to bloom, and if you continue to exude love, care, and patience she will respond in kind!