I never, ever announced a definate name. No matter how sure I was.
DD1 & DD2 were named before they were born, but we always said we were 'thinking' of this name.

DS was between 3 names & DD3 had no name til the next morning, & it was a completely different one to the only other one we both liked!

Maybe tell her you're having second thoughts about it??
I agree.... tell her you are thinking of a new name... then she won't keep usng it. It's your right to have the special and exclusive use of her name how you wish