Is there a level map in Transistor?
There is no level map in the game itself. I am also not finding one on any of the popular wikis.
There is, supposedly, a "debug mode" that allow map skipping/warping, which might help, but it looks like folks are having trouble downloading or using the user provided script.
The forks, in my experience, are usually dead ends or loop backs that do contain extra story telling. So, you might try a walkthrough.