As I said, Isaiah's the prophecy is very unusual. There are many unclear points and it is difficult to get a grasp of it all. In the midst of the Immanuel's prophecy, we have the prophecy of the Isaiah's own son, conceived by the prophetess, and not "the virgin" or "servant girl". So it seems to me that we have two prophecies and Hash-Shahs-Bazaar is completely separate from Immanuel.
What makes it difficult for me to take this as a prophecy of the birth of Jesus is that by the time Immanuel is a prepubescent age, the two kindoms mentioned become desolate. So there is a sense of immediacy (in number of tens of years and not hundreds - note 65 years mentioned about the Ephraim) to these prophecies. Yet, we sometimes see a pattern of recurrence (an immediate promise and a prophecy of its occurence in the far future - perhaps even multiple times). This pattern happens in the book of revelation. In fact, it is possible that this prophecy is one of these types. Israel falls around 30 years after Pekah, so desolation within 65 years completely makes sense.
As we said last time, the curd and honey is a sign of abundance:
"because of the abundance of milk that they give, he will eat curds, for everyone who is left in the land will eat curds and honey" - which refers to the prosperity of the Israel.
Now could this refer to Hezekiah's reign? Don't know. In any case, all I can say is that I cannot be sure this refers to the "Virgin Birth".