I want another baby!

I am 22 happily married and have 3 beautiful children(2 boys ages 4&1 and a daughter that is 2) I can't help it but I want another baby so badly. I only ever planned to have 2 kids but for some reason I can imagine having a large family (5+ children) and being completely happy with my life. We don't own a house yet we are still renting but I have a really good job and so does my husband but when it comes to another baby we are on completely different pages. Ugh why must this be so difficult????