You need a good instructor - however much you think you know your horse is telling you you haven't got it right. It's your responsibility to be the owner your horse needs, not for the horse to fit in with you, how would they know that?
Lazy and stubborn after having been fine before you bought her, what's changed? You, that's what. Get the idea that you are experienced out of your head, the best riders in the world acknowledge they still have loads to learn, if you are anything of a horsewoman you will take on board what this horse is telling you. She's uncomfortable, she doesn't understand, you are blocking her, she is worried, whatever it is you know the saying "When the student is ready the teacher will arrive". You have yours, learn the skills you need to get the best out of her.