No, it does not make sense. A girl is betrothed; if she intends to marry and have marital relations, that is how she'll conceive. No need to ask any questions.
Assumption of Mary is indeed not following from this verse. Her perpetual virginity is.
And why exactly, is "perpetual virginity" so highly valued anyway, when God said to Adam and Eve, and all creatures, to assist in creation by giving birth?
Don't be offended, but you sound like a child who thinks his momma had sex once and it resulted in him. Mary wasn't quasi God, she was just a human, which is what she had to be for Christ to be fully human. After she had Christ, her special mission was done. After that, her life was her own. As the bible says, she lived the life of an ordinary wife and mother, she did not go to a convent and seal herself off from the world.