I personally think you should take what she says with a grain of salt. I don't think you should break up with her or anything, but I also don't think you should place full confidence in the fact that she believes you are her whole world right now. To me, that sounds like someone that doesn't have a good, strong sense of identity, which could cause problems later on. I guess I would take it day by day. Don't throw yourself into this with utter and complete abandon (meaning, keep your own identity as an individual), but don't distance yourself from her to the point of being cold. You're only a month in. Day by day to see how things progress. I don't think you need to make a decision right now.