Yeah, I hear little ones in general can be defensive. Didn't know Sonorans were worse, but I don't doubt it. Behira was a little over 1 years old when we got her. She was with a small breeder who handles his animals, so she was already very chill. I also asked for his tamest BCI, any morph.
Keep working with her and you should get there.
Remember, snakes need a lot of consistency and reinforcement. They do not think like we do, or dogs, for example. You can't reward or scold a snake, so it just takes time and consistent reinforcement. Did I mention it takes consistent reinforcement and time?
Good luck!