Aye, there's the rub.
Much as I admire my grandmother, her devotion to childrearing, and her willingness to sacrifice materially for what she believed, I don't believe that a woman's body was designed to have as many pregnancies and full-term births as she had in a relatively short period of time. Her kids were primarily bottlefed, and her fertility quickly returned between children.
Had she been "ecologically breastfeeding," she'd have had five or six kids, not nine. That's a pretty big difference.
This is the heart of my dilemma. While I appreciate the quiverfull philosophy which reminds us that children are a blessing from God, not a burden, and that the abundance of children is a particular blessing, I also believe that God did not design women to have a baby every year, or even every other year.* A 2-4 year spacing between children is optimal for both mother and child. This allows a woman's body to heal and restore itself between births. It allows each baby to receive as much of the mother's physical nurturing as he needs, from frequent breastfeeding to help getting to sleep, for as long as he needs it.
Quiverfull appeals to me, but as the mother of a high needs toddler, I sympathize with parents who feel overwhelmed at the thought of another child. And as someone who is almost, but not quite, ecologically breastfeeding, I sympathize with those parents who aren't eager to change their parenting practices. (If I were taking that afternoon nap with my son, I wouldn't be typing this right now.)
*I should note that most quiverfull proponents stress breastfeeding, but I know few who completely practice all seven tenets of ecological breastfeeding.