The so called Quinisext Council does not qualify. It is not an Ecumenical Council as the Western Church never ratified it, thus it has zero authority.
It should be noted that the Perpetual Virginity of Mary was dogmatically taught by the Second Council of Constantinople in 553, which was an Ecumenical Council. Here is the relevant material:
"Additionally, we anathematize the heretical letter which Ibas is alleged to have written to Mari the Persian. This letter denies that God the Word was made incarnate of the ever virgin Mary, the holy mother of God, and that he was made man." (Sentence against the "Three Chapters")"2. If anyone will not confess that the Word of God has two nativities, that which is before all ages from the Father, outside time and without a body, and secondly that nativity of these latter days when the Word of God came down from the heavens and was made flesh of holy and glorious Mary, mother of God and ever-virgin, and was born from her: let him be anathema."
"6. If anyone declares that it can be only inexactly and not truly said that the holy and glorious ever-virgin Mary is the mother of God, or says that she is so only in some relative way, considering that she bore a mere man and that God the Word was not made into human flesh in her, holding rather that the nativity of a man from her was referred, as they say, to God the Word as he was with the man who came into being; if anyone misrepresents the holy synod of Chalcedon, alleging that it claimed that the virgin was the mother of God only according to that heretical understanding which the blasphemous Theodore put forward; or if anyone says that she is the mother of a man or the Christ-bearer, that is the mother of Christ, suggesting that Christ is not God; and does not formally confess that she is properly and truly the mother of God, because he who before all ages was born of the Father, God the Word, has been made into human flesh in these latter days and has been born to her, and it was in this religious understanding that the holy synod of Chalcedon formally stated its belief that she was the mother of God: let him be anathema."
"14. If anyone defends the letter which Ibas is said to have written to Mari the Persian, which denies that God the Word, who became incarnate of Mary the holy mother of God and ever virgin, became man, but alleges that he was only a man born to her, whom it describes as a temple, as if God the Word was one and the man someone quite different; which condemns holy Cyril as if he were a heretic, when he gives the true teaching of Christians, and accuses holy Cyril of writing opinions like those of the heretical Apollinarius ;which rebukes the first holy synod of Ephesus, alleging that it condemned Nestorius without going into the matter by a formal examination; which claims that the twelve chapters of holy Cyril are heretical and opposed to the true faith; and which defends Theodore and Nestorius and their heretical teachings and books. If anyone defends the said letter and does not anathematize it and all those who offer a defence for it and allege that it or a part of it is correct, or if anyone defends those who have written or shall write in support of it or the heresies contained in it, or supports those who are bold enough to defend it or its heresies in the name of the holy fathers of the holy synod of Chalcedon, and persists in these errors until his death: let him be anathema."
The last three were among the 14 anathemas against the "Three Chapters".
So we see a valid Ecumenical Council which dogmatically taught that Mary was ever-Virgin almost 140 years before the bogus "Quinisext" council.
Pray for JP II