How did you decide how many kids to have?

We want to start having children and we can't decide how many we want. (I know we may change our minds as time goes on.) Sometimes I think I'm better with kids one-on-one. My husband has said maybe we should only have one child cause it's not as stressful. I can't imagine not having more than one though.. I used to want a big family. I've always loved kids. I have three siblings and I can't imagine my child not having siblings! How did you decide how many to have?