Why do you really want 4? If you have 4, will you want 5, or 6? Being "born to birth" isn't the best reason to have children - being able to provide for and love your existing children is.

DH and I are arguing 2 or 3; I'm already upset there will be a very large gapbetween 1 and 2, but he is right that we cannot adequately provide for another right now.