What an interesting dream character, I love having recurring people in my dreams. It sounds really cool to me that you communicate with her with your mind.
As to who or what she might be, well that depends on what you believe about dreams. Different people will say different things - Some people will say that she is just a dream guide, some will say that she is an external entity that is there to guide you or just be with you or maybe even love you, some might even say that she is a latent part of you that is being represented. I think that whatever connection you have with her and whoever or whatever she is, it sounds like it's a special relationship that you have with that particular dream character and I think that's really neat.
I'm sorry I don't have any easy answers for you.
Who do you think she is?