Mecro,
I used to be as vocal as you (if not more so). The problem with that was that it was not the girls playing soccer, but me playing chess.
I still (U12 girls) occasionally remind the players where their positions are, or ask them to fill in for a player who has walked off in attack and never returned, but I would rather have them learn to play on their own: if one of them forgets where she is supposed to be playing - something that happens all the time - but the others remember where they should be, you all of a sudden get an unbalanced team. try teaching them the principles of pressure - cover-balance on defense and support (in front, behind and either side) on attack, and they will get into whatever formation works best for them.
With U10, what worked for my team was ultimate frisbee scrimmage at the end of practices instead of a soccer scrimmage: when their heads are not too occupied by looking down at the ball, they tend to get into positions on their own. We did it a couple of times, and after that they played soccer the way it is supposed to be played.
I also give them "homework": soccer diagrams of plays from the games they had. They have to make the decision for one or two "players" on the diagram. We spend 2-3 minutes discussing those at practices.
We don't win every game (about half), but they learn how to be self-sufficient on the pitch (and I learn how to be patient on the sideline).
Cheers!
-Alex