I haven't really heard the phrase "I have not been to me". However people do say "I have not been to myself (lately)" or "I just haven't been me (lately)". Most often the meaning is that emotionally they haven't been feeling the best so their behavioral pattern is different than what is typical. It's often said as an apology to friends. For example, if they go to lunch and that person has been upset about breaking up with her boyfriend so she does not participate in conversations with her friends, she may apologize to her friends by saying, "I'm so sorry. I just broke up with my bf 2 weeks ago and I have been so sad. I just haven't been myself lately."

I believe you might be thinking of the phrase: "I have not been myself" Someone would usually say this if something had occured in their life to make them dislike their usual activities such as going out with friends.

Another possibility might be the phrase "I've never been to me" which is a pop song. Different people have sung it, but I only remember this one: http://www.youtube.com/watch?v=05Dm9txyWac&feature=fvst In that song a woman says that she has done so many things in life and gone to a lot of different places, but she says, "I have never been to me," meaning she hasn't found her true self because she has been searching for "paradise" outside of herself.