Dream- for some reason I want to reply without (deliberately) reading other responses. I'll give my impressions, fwiw, it could be completely off base.
What a powerful session! T feels very connected to you as you do to her. And you are ALLOWING her to re-mother you. It is not a bad thing. She is and you are allowing this re-experiencing in a safe way. Especially the sadness. Then, after the sadness is out, she has experienced it with you, she takes you to someplace that can relieve the sadness. Weight and food and relationships. I see you as someone who would thrive in the right relationship. Maybe this is T's impresssion of you? The concept of your weight being the source of your pain confuses me, too. The feelings/actions that keep the weight on might be, but the weight itself, to my mind, is a symptom more than a source. Though the weight itself can hold people back, no matter what weight and be the more obvious source of pain (Im trying to understand what she might have meant). Unless....you are picking up on HER weight issues and issues with a person being overweight. It may NOT be only your issue. Just a thought. I thought that SO many times with dt, that after these last months of reflecting on it, there is no doubt that she had food/weight issues and was unable to deal well with mine.
Im glad you changed directions during the session to what you had in mind to talk to her about

It sounds like your little ones wrote a very touching letter to her, they love her and maybe she saw that love, after the rupture, as deeply forgiving of her. AND she may be such a skilled therapist that when she is at a loss for words, it is not obvious to you....or she find something she believes to be just as relevent to say even if she feels it isnt the right thing to say/do with you. Was it the weight/relationship/sex thing that you didnt want to talk about that she picked up on?
My feeling is, that even if it is an issue, what is pushing at you now is the mommy sadness and your little ones. And what they have to say. The issues around weight and sex will push at you when you are really ready to go there. Or even to say something about how you feel when she pushes and the weight issue. I dont know how you might word it, but you might convey to her that your concerns and fears about her bringing this topic up repeadly is that if she finds it to be such an OBVIOUS block to your progress, it must be because she has strong feelings about how you look.
I have to add, on the flip side, ftt does this in every session. From self-hate to food and weight. BUT it does lead me into the sadness and feelings of my childhood pain and why I am compelled to act out with food (which is not what you may be doing). I dont get annoyed with ftt for doing it, b/c I KNOW my ED can lead me to where I need to go with trauma b/c it is such an OBVIOUS symptom. I "wear" my issues wherever I go. Could it be that T sees you that way? Even if you dont see weight/food/sex that way?