I think it's cute. I love the name
Theodora, and while I'd use
Thea as a nickname,
Teddy would be cute as a pet name for a little girl. Not sure how it would hold up as she grew up, it's better as a nickname than a full name because of that.
I really like
Teddy for a boy, but unfortunately I read too much true crime and can't dissociate it from
Ted Bundy.