My current girlfriend is willing to play. In fact we have done some things in the past but she does not have a true dominant nature. I wanted to experience 100% submission to a true domme.
Just a thought, especially since your GF is willing to satisfy your desire to a certain degree, why not simply add play on an occasional basis as simply the odd fun night?

You already said you weren't interested in it 24/7, and she isn't truly Domme material, but what is wrong with enhancing your sex life with a "special" romp now and then? It will certainly, I believe, strengthen your relationship. Just get her to go more all out just for those nights?!