This has been a recurring issue with me too. Al of my ts talk too much and I have just begun to realise that they were teaching me something. To become more assertive. See I don't talk much and am naturally very quiet so that gives them some extra room to talk. I wish I could offer you some advice but I think it's a hard lesson to learn and it will keep coming into our life till we learn it. Your t seems very open to you giving her some more directions on how you would like your session to go. Do you think you could practise ways of being more assertive with her? I am sure she would be happy to experiment a little with this!