Wow, that's a hard one. I don't know if this is true in your case, but consider your non-verbal communication- it may be that since you are learning, your face does not show the "appropriate" expressions your preceptor thinks should be there, and that may be why she is saying these things about you. I'm not saying you're doing anything wrong, please don't think that, I'm just saying that you may be leading her to believe that you are defensive, etc just by your non-verbals- face, posture, tone and the like. I'm saying this because when I am learning something new, I look mean, but it's only me concentrating on learning. So now, instead, I just smile, and have a kind of light tone, and people "get" me better. I hope this is making sense & is helpful.