Felix, is there a possibility that after the hard landing the nose gear arm was loose, and during that takeoff roll
the gear hit a bump and was knocked off center? Also check the rudder / nosegear servo to make sure the
impact didn't damage anything or strip the servo.

Don't beat yourself up over a mistake we all made them and still do, You learned from it now finish the repair
give the plane the twice over and get back up there.

I had some problems with my front gear on my trainer, I found it easier to push the plane around when testing
instead of taxiing with the engine running. That way if anything was wrong I didn't have a chance to get nervous
do anything stupid. (It took me some time to realize that the ailerons don't affect ground steering)