Can you show anywhere in the OT where almah is used to refer to a married woman?
Most biblical scholars agree that almah is a young maiden, which presumably would be a virgin. However, in the prophesied event, the young maiden WAS married.
Not even Jewish scholars can point to a contemporary event (in Isaiah) that corresponds to this prophecy with any plausibility.
Your argument also flies in the face of Matt 1:23. Scripture is inerrant.
Since I have the software to make the task easy, and the time to do the compilation, here are all the occurrences of the Hebrew word
almah in the Old Testament:
Gen. 24:43: Abraham’s servant Eleazar is praying and asking for a sign, that the
almah (translated
parthenos in the LXX) will water his camels as well, when he asks for a drink.
Ex. 2:8, referring to Miriam, translated
neanis, “little girl”, in the LXX
Ps. 68:25, “among them were the
maidens playing timbrels,” again translated translated
neanis.
Prov. 30:19, “the way of a man with a maid,” translated
neotes, “female youth”.
Song of Solomon 1:3, “therefore do the virgins love thee,” translated
neanis.
Song of Solomon 6:8, “fourscore concubines and virgins without number,” translated
neanis.
And finally, Isaiah 7:14, which has already been dissected.
So, the answer to the bolded question in your first paragraph is “No.”