I am sure Paul VI regretted forming the papal birth control commission. The very act of forming it called the teaching into doubt, and the fact that the overwhelming majority opinion in favor of changing the teaching on contraception was made public seriously undermined Humanae Vitae. Even Paul VI himself, when faced with including the word "infallible" in the encyclical, struck it.
I admire your efforts, but I don't see how sermons or NFP seminars are going to put this genie back in the bottle.
We work with Engaged Couples Ministry in our parish, and nearly half the couples are living with each other when they present themselves for marriage. According to the diocesan director of this ministry, that comports with the general trends.
The exception are Hispanics, who generally marry OUTSIDE the Church and don't present themselves to have their marriages blessed until they're sure or until they're made to get married to have a child baptized.
Why do they choose to marry within the Catholic Church if they are effectively barring themselves from the Sacraments and living in a state of unrepentant mortal sin?