I will simply reinforce what has been said. Overall your setup is on the right track. I would absolutely switch from the Amsteel on the friction hitch to a good rated cord. There are some big concerns with using Amsteel where it will be subjected to the kind of friction the hitch will get as you rappel down.
It appears you have a traditional Prusik knot. If so, and that is what you prefer, the adjust it so that the knots forming the loop are not part of the actual friction. There are some easier hitches to use for this application, such as the Distel or Schwabisch. They’re less likely to just completely lock up, like the Prusik does.
The final suggestion would be with whatever hitch you settle on, shorten it up so that it’s not so close to the rappel device. If the hitch contacts the rappel device it can cause it to not catch and that’s bad.
Other than those suggestions, you’ve got a good system going.