I don’t think what you are describing is maladaptive daydreaming. The stories in your head are not interfering with your ability to function. You did mention that it may be a coping mechanism, but you didn’t give me information about what you may have been coping from when you were young. Yes, we all have to develop coping skills in order to manage an unpredictable world. But if you were coping from traumatic events, the scenarios may have been a way for you to escape whatever was going on. If so, it would not be unusual for it to take on a life of its own.
It’s also possible that you are a fiction writer in the making. Many successful novelists report that they started telling stories to themselves and others when they were young. Those stories were a way to get ready to be the writers they later became. I would hate to see that kind of thinking be pathologized into an illness. If that is true for you, maybe it’s time to start writing your scenarios down to see if they are the seeds of a novel.
The key question to ask when looking at any behavior is whether it is getting in the way of social, educational, or occupational functioning. If it isn’t, it isn’t a “problem” to be solved so much as an interesting idiosyncracy. If it is getting in your way, I hope you will make an appointment with a mental health counselor to talk about it more fully.
I wish you well.