Like a Virgin!

Virgin

Isaiah 7:14 says that a virgin will bear a son. The problem is dealing with the Hebrew word for virgin, which is "almah." According to the Strong's Concordance it means, "virgin, young woman 1a) of marriageable age 1b) maid or newly married." Therefore, the word "almah" does not always mean virgin.  The word "occurs elsewhere in the Old Testament only in Genesis 24:43 (”maiden“); Exodus 2:8 (”girl“); Psalm 68:25 (”maidens“); Proverbs 30:19 (”maiden“); Song of Songs 1:3 (”maidens“); 6:8 (”virgins“)."1 Additionally, there is a Hebrew word for virgin:  bethulah. If Isaiah 7:14 was meant to mean virgin instead of young maiden, then why wasn't the word used here?