Did I blow the rule?

[TexBlue]

ASA rules apply here.

Saturday afternoon, I was calling a 12-U game. A lot of bad feelings between the 2 teams. The batter hits a deep fly ball over RF's head. As she rounds 1st, she runs square into the 1st baseman who is looking into the outfield. A clear case of obstruction. Now, the BR looks at the 1st baseman, pushes her hard, back about 2 steps, and continues to run. I have my arm out for OBS, trying to quickly think of the rule for this. The BR stops at 3rd, I yell "Dead Ball!!" and talk to my partner. I then eject the BR for USC and put the substitute back on 1st. I have been looking through all 4 rule books that I call for and cannot find a situation where the USC warrants a dead ball except where the offensive player crashes into a defensive player who is holding the ball.

Am I missing the rule, or do you award the bases to the obstructed runner and then eject her? As far as I'm concerned, she was ejected as soon as she pushed the girl. All play should have stopped there, with no benefit from the OBS.