Annabel!! I love that name!! Though, I prefer the spelling of annabelle, as I feel the name looks more graceful and flowy with the le at the end. The name has never been wildly popular, so I think that's why people have a hard time picturing an adult annabelle. I don't find it difficult, but if I child felt they outgrew it they could always go by
Anne which is ageless yet mature.
Combos I like/love:
Annabelle CharlotteAnnabelle SophiaAnnabelle JulietAnnabelle JuliaAnnabelle Claire(We apparently have very similar taste :D)