It takes practice so don't be too hard on yourself.
Relax.
Remember to breathe.
Don't hold the handles too tightly.
No one stays on the line all the time. Those of us who do pantos a lot "wander" off the line.
My guess is that you are better at pantos than you realize. And remember, only you will see the line on the panto --- everyone else will see only the quilting.