Well, I think she did know who Jesus was, because as a young girl you just don’t get angels appearing to you telling you you’re going to have God’s son, and then you’re pregnant but haven’t slept with anyone. Further the wise men eventually finding them a couple years after his birth to pay homage to Him, and Joseph having the warning dream to flee to Egypt to escape Herod. I think like many Jews around that time however, that she (only in my opinion, mind you) may have thought that He would have at some point set up a physical kingdom during His lifetime then, somehow. Not being beaten, appearing to have lost and dying on the cross. I think she may not have known exactly HOW him dying and such was the method Christ would begin setting up His kingdom.
I think this is a possible explanation. Even in this case she really wouldn't understand the enormity of who He is which would explain why she would feel comfortable rebuking Him, or trying to exercise authority over Him by ordering Him to turn water into wine.