Your question B answers question A. Thus הָעַלְמָה (the young woman) was married but Rashi say was not yet pregnant with her first child.
That is Rashi and Ibn Ezra point to this pasuk to show that even if she was not yet pregnant, she was married to Yeshaya. Radak says that it was the young wife of Achaz
Those who translate the verse to mean is currently pregnant obviously state that the word הָעַלְמָהcannot in this verse mean unmarried. Additionally, they disagree with Rashi as to meaning that sh will become pregnant.
Ibn Ezra cites Mishlei 30:19 to show that the word cannot be virgin as
the way of a man with a young woman.
is given as one of those things that cannot be detected (after a short time). If she was a virgin, one could tell that she is no longer a virgin.
This also shows that it can mean a married or unmarried woman.
is with child: This is actually the future, as we find concerning Manoah’s wife, that the angel said to her (Judges 13:3): “And you shall conceive and bear a son,” and it is written, “Behold, you are with child and shall bear a son.”
the young woman: My wife will conceive this year. This was the fourth year of Ahaz.
This means that she was married, but had not yet conceived, but was about to in the near future.
Art Scroll Tanach translates it in accordance with Rashi (will become pregnant).