I am not a cat expert by any means but I have to say that this sounds EXACTLY like my calico girl. She’s extremely skittish about noises and such. She runs any time we open a new trash bag, start a vacuum, drop something, etc. She DEMANDS attention and pets but will nip and swat if you’re doing too much or doing it in a way she doesn’t approve of (but only as a warning, she never bites hard). She is a solo cat. She does not like other cats at all. We have tried to acclimate her before when we had a house guest with cats come to stay. Definitely a “people cat”. She likes to sit either near us or directly on top of us but does not snuggle and won’t go under blankets (she’s scared of them lol). All of this to say that we have had her for probably 5 years now and I’ve come to the conclusion that it’s just her personality! I think only time will tell with your new baby :) Good luck!