If the baby is a girl, Dorothea would have the nickname Dot, @magicstar2020 - that would be lovely.
I honestly don’t think Spike is a good name either - maybe as a nickname, but not their given name. It’s better than Ducky, but makes me think of the vampire in Buffy. You could use William (Spike, in Buffy, is William the Bloody), with Spike as the nickname.
Dusty used to be a nickname given to millers, if I recall correctly - plus the link to Dusty Springfield, which make it sound rather old fashioned to me.
You are naming a person, and I think you need to put their feelings above yours. Cute nicknames are fine for pets, but not such a good idea for children, I’m afraid. I’m not trying to be hurtful or rude, so I am sorry if this upsets you.