This, like generally Protestant translations, favors Protestant theology. My original says "I know not man", a statement akin to "I do not smoke".
I don't have any problem with your translation. It states a current condition without regard to the future. All smokers at one time could say "I do not smoke".
There is nothing in the annunciation to suggest the event is to take place before the marriage, and common sense would dictate that the it refers to the regular offspring of the marriage.
We have this:
Luke 2:5 : He went there to register with Mary, who was pledged to be married to him and was expecting a child.
We also have this:
Matt 1:18 : This is how the birth of Jesus Christ came about: His mother Mary was pledged to be married to Joseph, but before they came together, she was found to be with child through the Holy Spirit.
Doesn't this seem clear that they were not married yet? There is also the clear implication that at some point they did "come together" in marriage. They already were together in betrothal, so what does that leave?
This leaves us exactly were we were all along, that Mary anticipated being married to Joseph in the future, and the annunciation was also made about the future, so if she planned to consummate her marriage with Joseph in a sexual way she would not have responded "I know not man", because the fact that she was yet unmarried would not be an obstacle to her future marriage and natural motherhood.
Which version of the Bible says that Mary and Jospeh did "come together?"