We are to put God first in our life, and we are to read all of His word. If we love Him we are to be guided by Him, all of what God says. God says to be fruitful and multiply. That has been done. The problem was to be fruitful on the earth, now the problem is for the people of the earth to have enough to eat. We are to love and care for our family. There is no way for most to care for a large family, if we obey the Lord we must limit our family. We are not to withhold ourselves from our spouses except at certain times. We could not limit our family and obey this.
God supplies our needs, our need is to see to we can care for and love all our family. Our need is for birth control in order to obey all of God. God supplied us with this information, it would be wrong not to use it.