As you said so well, we cannot know what was going on in Mary's mind when she approached Jesus concerning the need for wine at the wedding feast. We don't know if she had witnessed "miracles" done by her son up to that point - notwithstanding those mythical writings called "infancy gospels" purported to tell of the young Jesus playing around with his "talent". Nevertheless, we know from the gospel of Mark that even after that miracle at the wedding feast, Jesus' family still doubted His purpose and abilities. In Mark chapter 3, we read of Jesus after he had healed a man with a shriveled hand in the synagogue - much to the consternation of the religious leaders angry that He did so on the Sabbath and it was from this moment that the Pharisees went out and began to plot with the Herodians how they might kill Jesus.
Jesus left there and went to Lake Galilee where He was followed by a large crowd of people who came from many towns all around to hear Him preach. He healed many there as well. It was then that Jesus appointed the Twelve among His disciples and followers. He then went to a house to have a meal with His disciples and a large crowd gathered there pressing in so that they couldn't even eat their meal. Then Jesus entered a house, and again a crowd gathered, so that he and his disciples were not even able to eat. Mark proceeds to say that "when his family heard about this, they went to take charge of him, for they said, “He is out of his mind.”" (Mark 3:20) And the religious leaders started accusing Jesus of being possessed by the devil seeing as He was able to cast them out of possessed people. I find it surprising that even Jesus' own family (we have to assume it included His mother as well as brothers and sisters) doubted His ministry and power. I seldom see anyone bring this up, but think it shows those closest to him - his OWN family - doubted Him. The Gospel of John says, "For even his own brothers did not believe in him." (John 7:5). As hard as it is to believe that the very people Jesus grew up with doubted who He was, we recognize that all-too-familiar human fault. People who SAW Him perform miracles right before their eyes STILL doubted Him.
I would give some leeway for Mary herself having not thought he was "out of his mind", but since his brothers did (as it is written) then it is easy enough to imagine they may have turned on Mary to a degree also -- if only to express to her face -- that Jesus is fake/crazy/out of his gourd loony, etc.
That consideration is part of why at the foot of the cross -- where I do think what Simeon had prophesied to her more than thirty years prior -- that a sword would pierce her own soul also --- came to pass, occurred right then and there.
For by then, Jesus's miraculous ministry, His way of speaking and being -- Mary herself likely had come to believe even as she may have yet still struggled to understand, and what all these things would mean for her nation & people, and herself also.
But then -- when that which many were expecting did not come to pass -- and the opposite instead, all the hope, the beauty, strength and wisdom of spirit -- which was her very own flesh & blood son also! --- was murdered almost right before her eyes, herself standing there as He took his last breath? all of that all at once is far too much for any human to endure, so what ever it was which pierced her soul, whether that have been some type of attack on her own spirit by forces of darkness -- or if that piercing was some act of mercy from God to stop the interior cycling within her heart and mind of the stark horror (her own son, with the flesh torn open to expose his ribs, beaten and bloodied beyond comprehension!) causing her mind and will to possible have shut down in part, leaving her at that point -- possibly so utterly wounded within her own soul ---- she may not have been able to find her way home...with no desire to go to that place, anyway, wherever that was, possibly in Nazareth, days(?) distant travel, away?
Her other children, acquaintances, and relatives from Nazareth possibly had disowned her as it were, leaving her now alone, facing what no other human being had -- her own son, who was as she knew the Son of the most high also, the very hope of her nation, the one Messiah, all of that brutally swept away, seeming to have made God himself into being a cruel tormentor also --- in how her own hopes had been built up to then be so horrifically and utterly destroyed...
Yet the disciple whom Jesus loved, John, was there beside her. Who else better in the whole world at that moment could there have been for her, to be there?
And then, be there closely with her in the days following, until the time of the resurrection, and also those 40 days when Christ appeared to 500 people, John would be there as a son to her, to look out for and care for her, to reassure her -- yes! He is risen! it is true! (don't listen to the naysayers). Ah, and she dwelt with that disciple for the end of her days, some measure of safety, with huge measures of real and actual understanding -- not just projections of empathy, but John having faced the horror of it all also -- though not wounded as deeply as Mary, oh no.
I don't think anyone can know just what it was like for her completely, save for the One who knows the inwards parts of all of us...
Now I do confess that I am speculating in much of this, yet I do believe I'm at least in the neighborhood of accurate guesses towards these things.
From that --- I do not believe that I should look upon her as my own mother per se, though one could also imagine that she came to understand much, and had a perspective towards these events unmatchable by any.
It seems to me your prophesying links the blasphemy against the Holy Spirit passage to the Feast of Tabernacles (Sukkot) passage, and implied that Mary, the mother of God with us, as well as other brethren (cousins of Jesus) believed he was possessed by an unclean spirit. Your use of "we" is troubling as well.