Are there abnormalities with your bone structure that could make you have an unstable gait?

Yes: There are several biomechanical conditions of the feet that can cause unsteady gait. It can also be leg hip or low back problems. See podiatrist or orthopedist.

Gait: Sure. Your legs could be different lengths. You might have some spur formation where the nerves exit your lower spinal column putting pressure on those nerves. You could have a stress fracture.