Doesn't solve the problem. She wants her to use her new name in public. Not her old name OR a nickname.

And then she has three names? That's not a compromise, that's giving in to the disrespectful gf. And she already said that gf can call her by the old name in private. The problem occurs when they are in public and she refuses to use the new name. Your suggestion won't solve that problem.

Which has absolutely nothing to do with this situation. It is OP themself who WANTS to use the new name. It's not being forced upon her.

This is the way!

This seems odd. Don't people in the entertainment business usually change their names before they begin their careers? It seems rather counter productive to become "mildly famous" with one name, then have to start all over with a new name.

But even when entertainers do change their names, aren't they often just "stage names" while they retain their birth names legally?

Seems like someone else made the best suggestion regarding your personal situation. Only your GF gets the "real" you. Everyone else only gets to know the "stage name" you. If she is unable or unwilling to play along with that and call you by your new name in public, then I would question how much she really cares about the "real" you. Because the real you isn't just a name.