This is SO interesting. My first reaction to it is that she doesnt have that motherly feel being thin. ANd somehow Bt did ahve a motherly feel to her. And maybe she has more of a motherly feel to her in emails with the things she says to you. But there is less "transference" with Kt than with Bt so the thrill isnt there.
I have a similar thing with ftt. She doesnt have a motherly feel to her for me. It isnt weight, it is something else. Maybe that she looks so young although she is a year older than me. Less transference. But then I KNOW I can work on my issues now without trying to undo/redo mother stuff. It was unfortunate that I couldnt have worked on my transference with dt. It wasnt for lack of trying. I tried to tell her my feelings but she stopped me every time. Even mid-sentence.

Well, I think this is GREAT material for therapy because it might be that it actually has very little to do with her weight in that it is associated to something for you. She sounds like a great T who can handle this stuff.