That's Interference!

[HugoTafurst]

I may always have looked at this wrong, BUT, I have looked at judging the base she would have gotten absent the obstruction more by judging how much I believe the player lost due to the obstruction.
In other words, brief contact rounding first or being denied the inside of first base while rounding, then getting thrown out by only a few steps. I would award her 2nd base, but if she continued (without hesitation) on to 3rd and was still thrown out by those same few steps, I would award her third.

If she were thrown out at 2nd by more than the few steps I judged the obstruction caused, I'd send her back to first.

If she were thrown out at 3rd by more than the few steps I judged the obstruction caused, she would be out.

Also if she stopped (or hesitated) at second on her way to third, I also would have no protection for her.