I read it some time in middle school, between 2002-2005. A teenager girl (I don’t remember her name) lives in a small town by the beach (on an island?). Her best friend is Bill (a girl), she has a dog named Deefer (as in “d for dog”; a boy makes fun of it), and there’s a stranger (drifter?) who comes to town. I remember it being a coming of age drama, but very little of the plot

I have no idea

This is like whatever book a girl living by the beach with friend and dog... But you can find it here maybe: https://www.goodreads.com/group/show/185-what-s-the-name-of-that-book