I'd start with things that will make it safer to handle her and go back to basics. Does she lead perfectly? Can you handle her feet, head, ears... without her protesting. Easier to figure this out now than with a tube of dewormer in your hand. Teach her to drop her head on cue. Only halter her when she responds to the drop cue. You can progress to bridling. Sounds simple but many struggle with such a basic and necessary task. Can she stand for hours without fidgeting? Work on sending. Stand to the side of a gate and send her though. When she hits the end of the rope, she turns and faces you. Safer for you than having her follow you through a tight space. Will help with loading as well. Work on desensitizing her to stuff. Clippers, vacuum, saddle blankets, fly masks (ripping velcro), the neighbors llamas, rocks on the side of the road, things around her legs... You can overdo it and make her dull but I'd feel better knowing how she's going to react to something before I got on her back. Work on flexing. Might reveal some limitations that need to be addressed.