If she really wants to do this because she feels it's her desire and not only yours, this might help. The Mistress Manual: The Good Girl's Guide to Female Dominance.
Be patient. Seriously. Dominance is not always easy to express, and the female dominants that I know often have often mentioned how difficult it was initially to push past societal conditioning on a woman's role. Hell, it is difficult for men due to societal conditioning that says "DO NOT HIT A WOMAN".
Just be patient and take the long view. You are directing, you are teaching.
Read a lot of books. Read a lot of threads in here. That will help a lot.
I don't think it's at all an error to consider a sub as a teacher, especially when a Domme is just learning where her power lies and what you both enjoy. I learn things all the time from my sub, both about him and about myself.
When I played as a submissive, it was with a relatively inexperienced Dom, and I did feel guilty sometimes about how often I felt like I was teaching and manipulating him. Eventually I realized we were helping each other, and that I could chalk most of it up to healthy communication. So relax! As she learns more about where your head is and what you'll respond to, she'll be more effective and more able to manifest her own power, and you'll be able to relax into being a sub more completely.
Encourage her to get some friends she can discuss this with other than you, she needs to find her own way among different influences, not just respond to one.