I have a 4 year old Percheron/TB cross. Lately, she has started resisting my cues for her to soften up her mouth and respond to my hands. She doesn't respect what I ask her to do, and tends to stick her head up in the air and go faster when I try to ask her to "come back to me". Sometimes when I need for her to slow down and relax and I pull back on the reins, it feels like I'm pulling a rope that's tied to a fencepost...she just doesn't give. She is fine sometimes, but other times she doesn't respect what I am asking of her, and is like a freight train that's on a roll.
I have her in a full-cheek snaffle right now, but I was wondering if anyone has any recommendations on a new bit for her. Something that would make her a little bit more responsive, without the harshness that some bits have. I was thinking maybe a loose ring copper snaffle...but I don't know if there's something better out there. Thank you!