As a former elementary school librarian, I'm familiar with
Felicity from the American Girl series.
Felicity isn't a particularly well-known character in children's literature when compared to other characters such as
Charlotte,
Olivia, and
Amelia. These popular girl names have more recognizable book character associations -
Charlotte from
Charlotte's Web,
Olivia the pig, and
Amelia from
Amelia Bedelia.
Felicity is a great underused name, and I wouldn't let the book character stop me from using it.