I think a lot of people name their children as babies and forget they’ll be adults for most of their lives, hopefully and typically.
Lucy by contrast is storybook sweet and also has a lot of academic gravitas for the adult years. I know several Lucys from age 10 to 90+ and it works at all ages and stages.
I must admit it’s not among favourite names but I can objectively see its appeal for the reasons above. I can’t see the appeal of Frankie (very honky, when the lovely Franny is right there ;)) - so not all cutesy names are good options! It sounds like Lucy has your heart. So try to trust yourself and let her grow into it. It’s a much loved, traditional and well established name. 