Look back rule

[Dakota]

You got it exactly right. Once R2 made that little step back toward 1B, she was committed to 1B unless the pitcher made a play.

As I understand your description, the pitcher did not make the play until R2 changed direction again and moved toward 2B. As soon as she changed direction again, DEAD BALL - RUNNER OUT. What the pitcher does during the dead ball is of no consequence. Return R1 to 3B.