Well if you are on different levels maybe you are just not right for eachother. If she wants you to be really harsh on her, and you are "softer" - then maybe you should look for someone else.
As for suggestions, it's hard to say without knowing anything about any of you. I would be demanding and tell her to either commit to your relationship or end it. Be imaginative and come up with a really humiliating/painful/whatever-gets-her-going task. If you feel she is challenging you, you need to challenge her with something harsh, show who is in control. Either she will do it and you will be back on track or she wont but then you will at least know.