There is a huge difference between boundary violations (such as sexually or financially exploiting a client) and boundary crossings. Boundary crossings are acts that are outside the usual structure of therapy by can have beneficial use (going for a walk during a session with an anxious client, giving an item that has meaning to the therapy work but is not high dollar value etc)
Her defensiveness is just not the sign of an effective therapist. Your negative reactions are normal and part of the work. She should not take it so personally.
What kinds of boundary issues do you mean? Are you comfortable giving specifics?