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If I remember correctly, it's to do with putting too much weight on the outside of your feet. So you would want to change how you distributed weight on your feet, and experiment with putting more weight on your large toes and the arch of your foot.
I am in a similiar position to you, attempting to fix scoliosis, and I am finding that really consciously walking with all the parts of my feet, pushing off and grabbing the floor with my toes and trying to push myself onto my heels. When I do this I walk more smoothly, and my feet feel achey - like they've had a workout.
I would also urge you to read Esther Gokhale's book on back posture, "8 Steps to a Pain Free Back". I have found it invaluable so far in informing me of what proper posture is.
Funnily though, one of my friends with the best facial form I'm aware of, has incredibly pronounced bow legs. He's not been exposed to all this mewing stuff, and assumes that bow legs are actually a sign of agility.
As you undergo correction in the near future, please consider keeping records for your own sake and for others. Pictures of dental impressions, scans, medical reports reports can be very helpful even with all personally identifying information blocked out.
Your input could help many, many people