Is this what Histrionic Personality Disorder looks like? I'm not at all labeling you. I'm trying to understand this dx better myself, and due to a family member.. and reading this post made me wonder. Worth a peek?
I'm wondering, because of your anxieties and introvert personality, seeking this level of attention in real life is scary. So naturally, creating a pretend world to get this attention, makes sense to me.
Does schizophrenia or other personality disorders run in your family?
I'm also wondering what your childhood was like. Did you often feel you were ignored or neglected? Were you a "middle child"? Do you know where this behaviour stems from?
I think it's common to have fantasies and I don't think it's a negative, either. Your concerns of it potentially leading into this gray area is a valid one.
Have you seen a counselor about this? You'd warrant her attention..?