God mother dilemma

My best friend had her baby last year and made me the god mother. Now I’m pregnant and we’ve already chosen the god mother and it’s not my best friend. Is this rude? How do I go about explaining this to her? She keeps bringing up god mother related topics and its making me feel so awkward. I love her to death but it’s just not what I want to do (for various personal reasons). Thoughts? advice? 😔