I am so happy for you and for LD! Lucky Dog is what I think it really stands for. Loving Dog, Little Dancer - with an initial type name, the list could do on forever! And I don't mind "little dummy" - when I was a kid, my big sister had a best friend whose name was similar to her own, so her friend (who was a very bright person, but without much family support from her own family) became knicknamed Dummy. That's really all we ever call her, in all love and affection, and even now, years later, I have to think hard if someone actually uses her given name.

Lucky Dog
Lovey Dove
Little Dummy
Little Devil (if he's ever naughty)
Lazy Dog
and even, if you're a fan of Arthurian legends

Lancelot DuLac !