Keep your shoulders a bit more up.
When your shoulders are hanging down, the purse will slip to the direction of the ground.
I've been told this has something to do with gravity.
You don't have different shoulders, you put them in a different position.
When you walk, make yourself tall, stand right up, shoulders to the back and the nipples straight forwards, you'll see, it will help.
On you tube I saw a movie how females walk, try to find it, maby you can do some advantage with it.
Good luck, you'll manage.