wanting another baby or just the idea of it?

We have our daughter who is 13 months. My cousin and his wife just had a baby and oh my gosh my ovaries ache. Holding that brand new little newborn caused a let down, my ovaries explaining, and just this nagging feeling that we NEED another baby. Now it's all I'm thinking about. I'm not sure if it's the idea of a teeny little baby, or if I really want to add a new family member to our little circle of 3. How does one come to this decision? My husband said let's talk about it when our daughter is two. But until then, what am I suppose to do?!! The uncertainty if I'll have another is eating me up ):