Horse is spoiled, best thing is wet saddle blankets.
Would imagine there are other areas she is testing you, but you are missing it.
And could be, your saddle is hurting, too far forwards, or your hands and seat aren't steady too.
Ride her out, and when she balks, just sit there. When she moves out, let her go on with no patting and no praising.
The only way to effectively deal with this, is to stick it out. Not battling with her.
That she will go on for you is good, but other than consistent handling of her, and no babying her, you just have to rider her.
Horses make me a better person.