Very common, your diagram looks like my set up. Spring
line works or walk the vessel on the port side as stated. Push your rudder hard to starboard so that the stern will want to go to port. Feather the engine just enough to get speed; if you hit it hard, the prop wash will pull you to starboard which you are trying to avoid.
Remember, the pivot point when backing up is at the bow so be patient when backing up. It takes time and you will feel her going to port, just ride it out.
Good post Alameda..........
John
s/v Daphne