I think that if it was me, I would not address this by saying about how you think transference/counter transference may be going on, and T is reacting to something the way mum often does. Rather I would try to directly address the thing that is bothering you with T: like I am (unhappy/confused or whatever) about how you said or did this and that, can we talk about it. I would try to dive in and discuss the actual situation in a direct manner, rather than through the lenses of transference/counter-transference.

Then if it is resolved well, it may really help in terms of having a better template, which may help resolve future things with your mum.

And if not, and it's still a problem or T hasn't engaged with what you said, maybe at that point raise the question of transference going on.

I don't know for sure that this way is better than another way, just saying this is what I would do if it were me. I think because that's how my T and I resolve things, we tend to be very direct, but then working through things with T helps me to have a better mental template for working through things with other people.