I understand the meaning. I object to the term. My earlier answer was in response to why I think using theotokos makes it more confusing. She did not give God a beginning. So therefore she is not his mother in the normal way that most folks would understand the word mother. Did God use her to become incarnate? Yes. I dislike the phrase though - plus, it and all the other "Mother titles" of Mary tend to elevate her to a level of devotion that she should not have. She is a role model. Was a virtuous woman. Is to be admired. She is not the queen of heaven, and given its context in Jeremiah would probably find the term abhorent. She is not the co-redemtrix. Her sorrow did not pay for my sins. Jesus's blood did. She is not a lot of things that have been thrown on her outside of Scripture. And don't you think that if the Holy Spirit comes and doesn't testify of Himself but of Jesus Christ, that Mary wouldn't draw attention and devotion to herself but to her Son?
You are free to dislike the terms. . You say that she is a virtuous woman? How virtuous? Do you draw any distinction between her and Elizabeth? There exist degrees of natural virtues. There exist different charisms. Some saints are greater than others. Mary a role model? Only as the model Christian. As the mother of Jesus, however, she was closer to Jesus--literally--than any other human being not just until she gave birth to him but afterwards. She was his mother. To say,as you and Nestorius siad, that she was only the Mother of Jesus, or the Mother of Christ is to try to separate his divine nature from his human nature. His human nature was as much the doing of God as his divine nature.