If I did end up using
Katharine, she might go by
Kate,
Katharine, or both. I really can't say for sure, but I do know I would NEVER call her
Katy /
Katie. It's just one of those things that you intend to call the child by a certain nickname but it morphs into something different. My mom never thought about calling my brother DSeay (
Daniel Seay) but it just sort of happened.
And I love
Kate as a nickname and full name. It's one of the few nicknames I think can pull it off in the full name slot.