I accept that you "personally" don't know how to understand the Hebrew text, as it was written in a language and in a culture that you don't have first hand knowledge of and that you don't have contact with previous Jewish generations who had been/have been learning, teaching, and living it - thus in your current situation it would be impossible for you to know what Yeshayahu or any other Hebrew writer (past and present) meant/means/ in text they wrote/or have written.
So, that being the case it is best for you to leave it to the us professionals who know it, live it, teach it, and continiously learn it from previous Jewish generations who did the same before.
I'm sure Matthew didn't see this promise in isolation. I believe he read it in the broader context of Isaiah 7-11, one of the key prophetic sections that point toward Jesus as Messiah. In Isaiah 7, he is about to be born; in Isaiah 9, he is already born and declared 'mighty God', the divine king; and in Isaiah 11 he is ruling and reigning in the supernatural power of the Spirit. As Matthew looked back at these prophecies, it would have been apparent that these chapters were linked together and that the promises of a worldwide, glorious reign of the promised Messiah were not yet realized. In Chapter 8, Maher-Slalal-Hash-Baz is born. It seems that for Isaiah's contemporaries, this birth virtually took the place of the birth of Immanuel, leaving this important prophetic announcement without any record of fulfillment for more than seven hundred years. Some people say that if Immanuel's birth was supposed to be a sign for Ahaz, then it wouldn't make sense that it would refer to the birth of Jesus seven centuries later. This fails to account for a few things. First, this was a promise to the house of David as a whole, and promises to Davidic kings often had meaning beyond their own generations. Second, the birth of Maher-Slalal-Hash-Baz seems to take the place of the Immanuel prophecy in terms of the immediate historical context. Third, the prophecy is shrouded in obscurity, and so Matthew could legitimately examine it afresh and seek its deeper meaning. I think Matthew's interpretation was legitimate. He sees the supernatural birth, this Immanuel figure, as part of a larger messianic complex of passages, and he applies this difficult part of scripture with genuine insight to Yeshua.