Well, as I know the story, she was engaged to be married to Joseph, which in that society was the same as being married only the marriage hadn't been consumated as indicated by the throwing down of the marriage sheet.
However, why would Mary and Joseph leave their other children and go looking for the one they finally found in the temple teaching the older men as an adult during the time of taxation?
Mary was about 12 yrs. old when she was bethrothed to Joseph and just after she was old enough to conceive when she became pregnant by the Holy Spirit.
It is of no importance what-so-ever either way to the historical and religious impact of the reason and reality of Christ and his ministry whether or not Mary remained a virgin.
She is of little consequence in the big plan except that she was the vehicle by which God came into the world. Maybe as an example of chastity and to show the suffering every mother has to bear who has children, but to assume that she is the mother of God is an insult to the almighty.
If it were true that Mary was on equal ground with God the father and God the Son and God the Holy Spirit would imply a four-sided God instead of a Trinity...