I would recommend sending her to pre-school at least twice a week. It sounds like it is time for her to spend some time where she is not the center of the universe
Especially since she will be in school soon.
Not being a smart alec
...seriously. I went through this with my daughter, sons, then later, my niece. It will make a huge difference for her to have something that is "hers" and allow her to become more independent.
"Center Kids" are notorious for this. My sisters (both school teachers) can "smell" them yards away. I am sure you remember some of the teachers kids back in school?
It can be hard to see when they are yours