I think the
Charter of the Rights of the Family is helpful here:
Take note of both parts here:
Yes, spouses may choose the number of children to be born.
However, they may not use immoral means to limit the family to this number or to attain this number (also excluded would be in vitro fertilization, surrogacy, buying/stealing children, and other immoral methods of having more children!).
This balance, I think, implicitly affirms something similar to what Veronica97 was expressing: Spouses may choose the number of children, yes, but they must also remain open to the possibility that their reality may turn out a bit different, that more or fewer children may be conceived or adopted than they had planned.