(It doesn't allow you to infer anything, even what's most obvious to all.)
Answer the questions: Why would Mary give her assent to the proposal Gabriel delivered, if her consent wasn't needed? Why does Scripture record that Gabriel's departure took place after Mary consented to the plan described to her?
Well, if I am required to read Mary's mind, let's see what I can come up with...
1. Who knows what goes on in the logic of a woman's mind.
2. She could consent or not, it WAS going to happen. That's what the angel spoke BEFORE she ever said anything to him (it?).
These angels are pretty smart dudes - Just as the angel foretold, Elizabeth conceived. While she was pregnant, Mary, the expectant mother of Jesus, visited her. The baby in Elizabeth's womb leaped for joy on hearing Mary's voice. Elizabeth gave birth to a son. They named him John, as the angel had commanded, and at that moment Zechariah's power of speech returned.
I think you have that exactly wrong.
All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work. 2 Timothy 3:16-17
Emphasis mine, to help you through it.