So the old testament is saying "Behold! LOOK! Be amazed!" a young woman shall concieve and give birth.
Really? They were surprised or astouinded or asked to take special notice of one of the most common things in the world - that a young woman gets preggers? That's what faith was saying about the context strongly indicates virgin. Even if it doesn't the NT is clear that Mary was a virgin when she gave birth to Jesus. -That's kinda why it was called a miracle.