If I recall correctly, OP is actually autistic so they are probably aware that autistic people have emotions. I think they just meant how the therapist comes across. OP probably doesn't require psychoeducation on this point from neurotypicals.

ETA - OP, I recall you mentioning elsewhere that you've been suffering from a sleeping disorder. I imagine you're pretty tired. Maybe she's mirroring you - if you're low energy and sort of flat, she takes your lead and acts the same. Some therapists do this.