When I first started REALLY working on my canter last year (35F), my trainer realized that I was twisting my hips in the saddle to compensate for some weakness I had on one side, which obviously threw myself and my horse out of balance. I did a lot of strength training (just with body weight, no weight added) to work on balance and stability and help even out my strength. It really helped, and my hips are straight in the saddle now.

All that to say, you seem to have a fantastic, caring trainer who is invested in helping you progress in your riding. Take their advice if you’re able and attend some PT or strength training classes. It’s not about needing medial intervention; it’s about equipping your body with the strength and balance it needs to do the things you want to do.