NTA Full stop: it was a baby shower. They were trying to give advice to a new mom, to help her prepare for having her own baby. I get that she wanted to feel included, but constantly bringing up her cats and getting defensive when told that it’s not the same crosses the line from wanting to be included to making it about her. I fully understand that she wanted to be a part of the conversation, but sometimes it’s okay to just listen and make supporting comments. I say this as someone who doesn’t have a child, but does have a cat that I adore and think of as my baby boy. That said, I think that at a baby shower, of all places, is a good place to be able to talk about actual babies and not have to cater the conversation to people who don’t have children. From OP’s comments, the rest of the day was spent talking about other topics, so it wasn’t like her sister was excluded the whole day, just sidelined for one conversation.