All of the sources that you cited are quite late, except for the Protoevangelium of James. That bolsters my argument that the perpetual virginity was a later invention that was not held by the early church.
Note that the Catholic Encyclopedia describes the Protoevangelium of James as "based on the canonical Gospels which it expands with legendary and imaginative elements, which are sometimes puerile or fantastic ..." Not exactly a good book to base a doctrine upon.
I also cited St. John Chrysostom, who I believe you cited as well.
I wold also point out that a host of "beliefs " regarding the divinity of Christ, the nature of God etc were making the rounds during the very early Church so finding some one who held an opinion at odds with the true Church isn't that surprising.
If the early church believed that Mary had other children, why do the two churches that trace their roots back to Christ and the apostles not hold the same view as the reformers? Why is this an issue for non-Catholics and non-Orthodox?