You asserted: “ I rely on what has been taught since the beginning, by the great majority of churches, everywhere around the world, and confirmed by the successor to St. Peter, the head of the Apostles. The minute I find my position wrong, I *change my position*.” Two maybe three presumptions not provable in the inference that you *might* be found in error someday! LOL, you have not a clue how led by a deceit-ring in your spiritual nose you are. {HINT: the ‘head of the Apostles was The Holy Spirit, as Jesus tried to teach you. But then as a Catholic you probably believe the Catholic Mary was the head of Jesus for some undefined period of time in His ministry mission, and continues to prod Him to get prayers answered!}
There is heavenly headship, and earthly headship. Peter was the head of the Apostles *on earth*.
http://www.biblesprout.com/articles/salvation/peter-keys-heaven/
Does the Holy Spirit discipline heretics? Cast them out of membership? Preside over synods? Confirm doctrinal formulations?
Of course nothing Peter said or did could ever contradict or usurp the Divine Authority. But Christ gave him the keys over the earthly government of the church, and no mortal man has any right to revoke that.