Hi Aspie Otaku!
I tend to get very engrossed in what interests me at the moment, also. And, I talk to myself, too, sometimes. Don't worry about that. More people do that than you may think. There are three kinds of talking to oneself. The first when people are rehearsing something. The second is a way people have of helping themselves think, or plan, or remember things. There is nothing wrong with those two. The third way is when you are holding "real" conversations with real or imaginary people or things who aren't there.
Besides helping myself think by talking to myself, I have heard others doing it, too, while I have been out running errands. There is nothing wrong with this.
I did encounter someone with mental problems once during a stay at a homeless shelter. He was out in the parking lot alone, but arguing to immigration people who were not there, about his immigrant girl friend, who was also not there. He had some other mental health issues, too, so the staff contacted the authorities to get him housed somewhere more appropriate, as the shelter staff is not trained to deal with mental cases.
Here at WP you will get help with your questions about your symptoms and problems. You can get help with a lot of other issues, as well. WP has a lot of different forum categories on different topics.
Hope you enjoy WP! I do!
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If a man does not keep pace with his companions, perhaps it is because he hears a different drummer.
Let him step to the music which he hears, however measured, or far away.--Henry David Thoreau