I am not an umpire, but I would say that this rule would apply:
NSA Definitions:
Sec. 40 OBSTRUCTION: Obstruction is the act of:
A defensive team member who hinders or impedes a batter?s attempt to make contact with a pitched ball, or who impedes the progress of a runner or batter-runner who is legally running the bases, unless the fielder is in possession of the ball or is fielding a batter ball. The act may be intentional or unintentional, physical, or verbal.
Now all you have to do is have the umpire agree with you. ?In your situation, I would have probably chosen another time to fall on my sword. ?I would bet that the umpire saw it the same as you and that it wasn't effecting the batters and let it go.
I wouldn't have your dugout yell back at her during the pitch, because that too is in violation of the agreed upon rules.