I'm in camp
Dory, as far as what nick I prefer for it. I'd call a daughter
Dory or
Dor.
If she were my best friend and saying her full name all the time felt weirdly formal, I don't know what I would call her. I'd ask her if I could call her by a nick and what it was.
People might come up with private nicknames for a
Theodora who didn't go by a short form, not as a change to her name, but just affectionately, for their own use and nobody else's. Because the name is just a ton of syllables to say. I think private nicks make it clear there is no assumption that you would answer to a regular short form of your name that is assigned by someone else, and anyway they can be declined.
I don't think it's very thoughtful of people to shorten the name of a baby in any way, though, since a baby doesn't need to be addressed, and can't decline a nickname. And anyway, using short forms for babies is a parent's prerogative IMO. It might be inconvenient to refer to someone by a full name but I think nicknames are for address, not for referring to people and using nicks to refer to someone who doesn't explicitly go by them is kinda disrespectful.
- mirfak