Conformation issues are so finicky. I know a [Saddlebred] mare who is toed out equally an all four feet, and she has a really long back. She has one of the smoothest trots I have ever seen, and somehow travels straight. She has the most beautiful spanish walk too. She has her issues, especially with her heels and she had pancake hooves at one point. She needed a lot of work to get to where she is today.
Have you ever had a therapist (bowen, acupuncture, pressure point, deep muscle, chiropractic, etc) look at your mare and see if she is "off" anywhere that might lead to her imbalance? If she's naturally a klutz, well, ****. But I'm curious if there might be an underlying issue that prevents her from carrying herself well. I find that horses, even with some seemingly outrageous conformation issues, can still be taught to travel and carry themselves well despite.
Keep up the great work you've been doing with her, keep her healthy and happy. And if semi-retirement is in your plans for her, that is alright too. You have a lot of years left in her yet. Enjoy them. :) To hell with what other people think.
Think of it not as a failure but as a success in how not to do it.
Don't look in a horses mouth for a gift.