Finn i guess isnt bad, but i dont think I would use it for my own child. I do not think
Finn is too short to be a full name, but I see where you are having trouble thinking of a middle name for just
Finn. Maybe you could consider
Finlay with the nickname of
Finn.
Finlay DavidFinlay MaddoxFinlay IsaacFinlay Garett
Finlay JacobFinlay JoshuaFinlay JacksonFinlay Colton