I think it's normal to play out conversations in your head. I do get stuck in loops also, obsessing about how I would like something to turn out.

Now for me, I have a bit of a different thing. I have another person thing in my head. She's part of me, but she's not me. She's Other Me. She helps me with things and is my friend. I talk to her all the time both out loud and in my head. She doesn't come forward and is more like a guide or an advisor or observer. But, I know she looks different than me. Other Me has been with me for a long time, so long I don't even remember her not being around.

Normal or not, I like Other Me and I'm glad I have her actually.