I "feel" myself not centered on my horse. Always thought the stirups may not be even or the saddle had slipped. Yes, my posture needs improvement but (really) I've been working on it. Never thought of getting therapy????
The is help for crooked riders. The Feldenkrais Method is the jewel. You learn to sense asymmetries and how to unravel them to the benefit and enjoyment of both horse and rider:)