Runner on 1st. I was the home plate ump. Pitcher pitched ball, ball went under catcher and got stuck between my feet. Catcher started reaching for it and I tried to get out of his way. However, in trying to get out of his way I accidently kicked the ball away. Runner on 1st has stolen 2nd in the meantime. I call ump interference based on the fact that I interfered with the catcher's throw and send runner back to 1st. Nobody complained, but I left wondering if that was the right call. If I did indeed interfere with the catcher's throw I know it was the right call. But I'm not sure that I technically interfered with his throw as he didn't have the ball yet. Was I right or wrong?

Your instincts were correct. That was not umpire interference. Technically.

You can't make a throw UNTIL you have the ball. The rule is very clear on that. There was NO interference here.

Bob