How did you know?

How did you know you wanted another. Lately ive been wanting more babies haha. My youngest is a year old. I have three. I've said that if im gonna have three then im gonna have four(Iwas a middle child and don't want that for my kids) I have three now. Me and my SO would joke about Having a fourth but PP was hard for me anxiety wise. I feel like If SO took Paternity leave for four month then it would be alot easier. I would still have 9months of Matenity/paternity leave before having to decide to go back. Idk now he doesnt want one but I kinda do.

How did you know or decide?