I would be grossed out too at the suggestion it was my mother I 'really' wanted to hold me - no way.
Like. BLT - my mother held me too. In a lot of ways she was a so called typical middle class housewife married to a man of good standing in the community. She baked us birthday cakes and held us birthday parties. She knitted and sewed my younger sister and I matching outfits. She fostered our love of reading, took us to the movies, on picnics, ice-skating. In winter she even stood outside in the cold night and hosed the driveway for half an hour so it would freeze over overnight so my sister and I could play ice-skating on it in the morning. She woke us at 3am on a school night so we could see snow falling for the first time. She helped me decorate my bike to out into a competition (which I / we won). She filled out my baby book and kept all my birthday cards, gluing them into scrapbooks. She also keep our best baby clothes and blankets (I still have these). She would care to our scrapped knees and bee-stings. She would sit with us on the couch and hold us tight.
But she was also an alcoholic addicted to codeine and stole to support her habit, spending more than one afternoon in the prison cells and many convictions for stealing to her name. She lashed out when angry, gave me black eyes and bruises so sore I couldn't sit. She shut me in confined spaces and rubbed my face in my dirty underwear when I had an accident in them (too scared to come inside to use the toilet).
I don't even want the 'nice' mother in her to hold me in my dreams. I was very afraid of her and I truly believed she would kill me one day in one of her rages.
I agree with AG - it might not necessarily be your mother you want to hold you - but A mother - the type of mother you didn't have - one that meet your needs and left you feeling safe.
I can't speak for you, but if my T said that to me (that it's really my mother I who I wanted to hold me) I'd feel invalidated - I'd feel like she wasn't hearing me. I 'get' transference but I don't always think it is transference (if that makes sense). Maybe sometimes it IS our T we would like to hold us, because intuitively we know they'd make a better mother figure?
I think you're very brave sharing yr dream with your T; doing so opens up huge possibilities for exploring old pain and loss (with the chance if healing)