Your argument is with the Holy Spirit who inspired the writers of Scripture to use the term *mother of Jesus* to identify Mary.
How ironic that Catholics, who claim the Catholic church wrote the Bible, criticize someone for wanting to adhere to the integrity of the Scripture that they claim their church wrote.
Where does Scripture teach that it is forbidden to invent new titles for anyone?
It is not “unfaithful to Scripture” to call Mary “the mother of God,” because Scripture teaches that:
Mary is the mother of Jesus.
Jesus is God (i.e., the Word).
Anything that is logically REQUIRED by what is in Scripture is taught by the Scripture.
Therefore, Scripture TEACHES that Mary is the mother of God.
Scripture TEACHES that Mary is the mother of God even though Scripture does not use “mother of God” as a title for Mary.