Why don't you learn to back the boat into the slip? Sure is easier to pull out of a slip going forward, and coming in you have more opportunity to overcome the prop walk and get her going straight back in.
Here's how I do mine:
Back the boat slowly into the slip and get the spring
line on her as close to amidships as possible. At the same time, have your mate grab the bow
line (now the "bottom"
cleat on your drawing) and tie it off. Keep a little reverse on her and she'll pull herself up against the dock because of the action on the spring line. Once she's there you can put her in neutral, tie off the stern line, and Bob's yer uncle!
Exiting the dock then becomes much simpler with a straightaway pullout.
Good luck, whatever you do!