Do you think that she is afraid that your changes are an act? If thats the case then all you can do is keep it up, eventually she will have to know that this is who you are now.
I wonder if you asked her why she feels like she has to fight it so hard, she would tell you the truth? Maybe just validating her explicit concerns would help her. Im not talking about her just saying "Because Im scared" Im talking about her saying "?Im scared that you have not really changed, that you will still ______" fill in the blank. Then you could ask her, how would she know that you had made that change for real. Im trying to think of solution-oriented ways to have this conversation.
I guess I gave the wrong finger to the wrong man...