Here’s my 2 cents…some Catholics will tell you that unless you’re going to die or be homeless, you have no reason not to have more kids. I tend to take a bit of a softer approach.
Here is what Greg Popcak says in his book For Better…Forever. We need to discern “God’s will for the size of our families” and “we are obligated to consider the resources or lack thereof he has given us to provide for the physical, emotional, and spiritual needs of a child. When parents’ physcial, economic, emotional, or physchological resources are lacking to the degree that they cannot adequately provide for a child’s mind, body, or soul, the Church invited the husband and wife to persue another kind of joy, the joy that accompanies mastering one’s sexuality.” He then goes on to discuss spiritual sexuality.
We are currently postponing pregnancy because I want to be able to breastfeed my daughter for close to two years; I know she is not ready to wean. I know there is a good chance that I won’t be able to continue if I am pregnant. I am providing for the physical needs of my daughter. I have no doubt that I am doing what is in the best interest of my family and that it’s not a selfish need. Others here may disagree, but that’s fine with me.