Has she ever told you *before* she goes? If not, it's possible that although she is interested, she simply doesn't recognize her urges. Just a thought.
My daughter is 2 1/2 and we have been introducing her to the potty for almost a year now. We started out with her own potty chair, she wasn't to comfortable with it so we bought the seat that goes right on the big toilet. Much better. She really started dhowing interest in the potty about 6 months ago, so we would take her into the bathroom and she would go. We have tryed the pull-ups, but she just thinks of them as a diaper and has no prob. going potty in them. So we put her in underwear and she still goes potty in them. The only time she will go potty on her own is if she is naked, not the best solution. She also never tells us when she has to go, we always have to just make her go, and she does. I don't know where to go from here, can someone please give me and idea of what to do now!