Play at plate

[Duke]

NFHS - Maybe HTBT.

Runner coming in from 3rd on passed ball. Pitcher comes in to cover plate. Pitcher is about 2 ft up the 3rd base line and steps in front of the runner without the ball. The runner had no time to avoid the collision. We have a "big" collision. The runner falls over and past home plate without touching it. Both players lay on the ground for a few seconds and the catcher comes back, picks up the ball and tags the runner just as she is diving back into the plate. I called obstruction on the collision but then think she has missed the plate so I no longer protect her and call her out on the missed base appeal. I now have both coaches coming at me. Defense coach wants interference for the collision and player thrown, offensive coach wants the obstruction. I confer with my partner and we decide that the obstruction caused the runner to miss the plate and award her home.

How would you have made this call?