Agree with above. If you want to be a bit persistent, respond politely to your professor, agreeing with her comments but clarifying that it was your understanding, per the instructions , that you were not to change content, but that you wanted her to be aware, in your side comments, of your additional thoughts about this composition and how you would have liked to have taken it in a different direction if it was permissible, but your understanding was that it was not. Agree with her comments but ask her to kindly reconsider the grade in lieu of your strict following of the directions. If she doesn’t le it go.