Stuff her (towels work well) and let her rest. A light 'treatment' with a warm blow dryer (not hot) held at least 8 inches away from the leather, might help relax the creases.
Also hanging the bag by the strap, will let gravity do some of the work.
You could add two (unopened ) 8 oz. cans of soup or vegetables to the inside for extra weight and hang the bag over a chair.
Thank you! I will try that.