Thanks MIEventer, very helpful! It's a little hard for me to sit in the "full seat" in the canter (and even trotting) due to my vest. I got the recommended size (XS for me) but it is STILL very long in the back, which causes me to tilt forward since it's hitting the saddle.
Any pointers on how to adjust?? I don't believe they come in length "short" haha! I wish they did, my torso is so darn SHORT nothing fits me correctly I swear!