My wife and I count ourselves very fortunate to have 12 children (3-26) and 3 grandchildren. I don't believe we're any more blessed than my sister who has 2 children.
Blessings and grace in the married state come from the openness of bringing forth the children God wills for each of our families.
My sister has had several miscarriages in her journey of motherhood. Doctors told her she would never be able to have children...my sister and brother-in-law were devastated. However, they always remained open to the possibility that God would bring forth life...lo and behold, they have 2 healthy boys. They continue to remain open to God's will.
Patience, charity, prudence, love, faith...these are just some of the virtues we are afforded many opportunities to practice each day in our family. There is no shortage of practicing and offering up some sort of sacrifice each day.
As married Catholics, if we remain open to God's will, and unite our will to His regarding the size of our families, we will be blessed no matter how many children we have. Catholic families come in all shapes and sizes, but it's our openness to bring forth the children God sees fit to give us that matters most.