I think you do have a horse that is a little bit on the high strung side. That’s ok, I hope this will help. I think lunging your horse before you get on her and ride off is a good idea, but when you lunge her don’t let her canter. If you think that lunging is only for horses that you are training, that is false, cause when you lunge them and do your ground work each time before you ride, it keeps them from having to go back to training. And all you have to do is maybe correct them. When you lunge her and she is cantering or galloping, she is always thinking fast. Backing a horse up before you take off to ride, helps a horse be in the mind set to think and use their brain. Hope this helps!