At my past lesson my trainer really focused on that I should keep my leg BEHIND the girth which I "got", but every time we started trotting it was really really hard to keep it behind the girth. Any tips for doing so? Thanks
I have the exact same problem- had it for a while- you're keeping your heel down right? Sometimes if I don't keep my heel down, my leg tends to slide forwards to the point where my stirrups gravitate near the middle of my foot. This also makes me post awkwardly sometimes. Still working on it.
Not sure I understand what you said, but I think in the title is where the problem is: it is NOT keeping the HEEL behind girth with the leg SQUEEZED.
The horse is meant to be ridden 'in position' (flexion to the inside/even bending through the body. That means the hips are parallel to horse's hip and the shoulders of the rider parallel to those of the horse. So legs are extensions of the hips.
That means the inside leg is slightly closer to the girth/inside heel a little lowered/weighted which 'bulks the calf' so when the horse's belly swings against the calf, the horse feels the aid. The outside leg is stretched from hip to heel PASSIVELY slightly down and back (foot still relatively parallel to horse). There should be NO squeezing with the outside leg or pulling it (up/back) into the horse.