The only official doctrine of the Undivided Church (and of the Orthodox Church today) regarding Virgin Mary is that she is the Mother of God (Theotokos). This was proclaimed as Church dogma in 431 at the Council of Ephesus.
There is not a single instance where she is officially referred to, 400 years after Christ died (5th century), as "ever-virgin" by the supreme body of the Church, individual authors' and Church Fathers' personal views notwithstanding.
Mary is the Mother of God only in that she is the mother of Jesus.
As many have agreed, Mary does not precede either the 1st, 2nd, or 3rd persons of the Trinity, nor did she give rise to the eternal Godhead.