You have a great question and I had once shared the same concern before turning our family size over to Him. I have used bc in the past also. Now in hind sight, I believe that I was not allowing God to control our family size because of man and the world's opinion of how many children were right for us. God only knows that. He knows more about me than I knew of myself which is why he has blessed me to have more dc. I also believe he has a wonderful sense of humor in doing this. LOL I believe that if God wanted us to use bc then He would have said be fruitful and multiply according to your needs but I don't recall that part in the Bible. LOL! We are to be fruitful and multiply and He also said that children are a blessing from the Lord and blessed are they who have a quiverful. How can we withhold God's blessings for us? Why do we want to control His hand or place restrictions on our wombs because of our wills? We are to do according to His will so is controlling your family size in His will? It's a matter of faith. Believe and trust that God knows exactly how many children HE wants to bless you with and He knows what you are capable of handling. Being a mother is a ministry. He will equip and enable you to do that which He has called for you to do.