What is this, or do "normal" people do this, or is it a product of my past abuse?

I have conversations with other people in my head. Real people, my husband, therapist, people at work, etc. mostly, sometimes fictional, sometimes no one. Not conversations that have already been had and replaying, but unique, individual conversations.

This morning on the way to work I was having conversations with my therapist. I would say something then I would be him saying something, not actually hearing his voice. I guess telling myself the things I want to hear.

Then I made up a story in my head when I saw a bus that had a unique kind of skirt around it. I made up this story about how it makes the gas mileage better and how one guy invented in and tested it on one bus and the people at the school board noted that it only saved a few dollars a month, but the guy argued that added on each bus a few dollars a month would add up to $1800 a year and that would at least buy band or sports equipment.

WHY am I making up stories in my head!!!