I don't think she should have brushed it off it is a problem for you and concerns you. I think it is better to nip it in the bud so to speak, because when I developed anorexia it started with just a little preoccupation and got much worse. That being said, when recovering from anorexia, my T wanted to talk about it all the time, including my weight and potential reasons behind it and I found it detrimental because it was a symptom of other issues and this just resulted in my focusing on it more. I found focusing on it made it worse. Maybe this is what she is concerned about and wants to focus on what she considers underlying/pressing issues. I think it is reasonable for you to inquire about this directly and say that it concerns you and that you want to address it before it gets worse or something. She should take you seriously. I think it's great you had the courage to bring it up and not hide it. Also, I was self aware, too and didn't know how to ask for help so I kept it a secret. Being self aware is a good thing in my opinion because you know you have a problem. Take care!