The New Testament isn’t a definitive source for everything that happened to Jesus, Mary or the Apostles.
The last verse in the Gospel of Johm states, “But there were many other things which Jesus did; were every one of them to be written, I suppose that the world itself could not contain the books that would be written”.
We should not rely so heavily on scripture that we take a position that almost denies that something happened because it is not stated in scripture. I believe that that is an error that many of our Protestant brothers and sisters in Christ make.
We rely not just on Scripture, but on Tradition and Magisterium. And if the Church, with the authority given her by Christ have declared as dogma, the Annuciation, then that is what happened. The Church existed before the New Testament and it was that Church that, through her authority, declared what scripture was to make up the New Testament.
Scripture does not take precendence over the Magisterium, just as the Magisterium does not contradict scripture.