Well, it turns out I didn't have as much in my document as I thought. I remember that I quit working on it when I realized my problem with Mary's ever-virginity had little to do with Scripture and everything to do with Western attitudes towards sexuality. Looking back over it, I'm not sure why I thought 75% of it was even relevant, so I won't post the whole thing.
What I had been looking for at the time was the earliest clear statements regarding Mary's ever-virginity, and the earliest statements in opposition (I did not include the Protevangelium of James
since, still being a Protestant at the time, I treated it as apocryphal). The primary things I found were: Clement of Alexandria, The Stromata,
from book 7, chapter 16 (written between 192-202 AD)
But, as appears, many even down to our own time regard Mary, on account of the birth of her child, as having been in the puerperal state, although she was not. For some say that, after she brought forth, she was found, when examined, to be a virgin.
Now such to us are the Scriptures of the Lord, which gave birth to the truth and continue virgin, in the concealment of the mysteries of the truth.
this does not directly address the ever-virginity issue, but I couldn't imagine anyone believing in her virginity after childbirth while not also believing in her ever-virginity. So, I counted it as supporting ever-virginity. Hippolytus, Against Beron and Helix,
from fragment 8 (around 220 AD?)
But the pious confession of the believer is that, with a view to our salvation, and in order to connect the universe with unchangeableness, the Creator of all things incorporated with Himself a rational soul and a sensible body from the all-holy Mary, ever-virgin, by an undefiled conception, without conversion, and was made man in nature, but separate from wickedness: the same was perfect God, and the same was perfect man; the same was in nature at once perfect God and man.
This was the earliest use of "ever-virgin" that I found. Athanasius the Great, Against the Arians,
Second oration, pgh. 70 (between 356-360 AD)
Therefore let those who deny that the Son is from the Father by nature and proper to His Essence, deny also that He took true human flesh of Mary Ever-Virgin;
This one is from much later, but several commentators seemed to treat Athanasius' declaration as kind of "nailing the issue down", so I noted it.
The closest I managed to come to a dissenting voice (I thought) was this one: Irenaeus, Against Heresies,
Book 3 (written c. 182-188 AD)
To this effect they testify, [saying,] that before Joseph had come together with Mary, while she therefore remained in virginity, “she was found with child of the Holy Ghost;” ...
However, Irenaeus is really just quoting Matt. 1:18, and I later learned that this passage (along with the "until" a few verses later in v. 25) had been pretty thoroughly explained. John Chrysostom's sermon on that passage cleared up any lingering doubts on the issue. Nothing else I dug up even came this close to dissenting. I did read some claims that Tertullian did not believe in the ever-virginity of Mary, but did not find any references I could check.