You always inspire me with your decisiveness and how quickly you get things done.
My ds was/is also very intense, and 4 is a super-intense age. I used to be shaking by his bedtime almost every night. He did not need a lot of physical contact with me, but he wanted it from df, so maybe it's a mother/daughter, father/son thing.
I think I did take ds to meet my therapist around that time, and another time to a child psychologist. I don't know if it was the same year. My concern was that he was too unempathetic, but my therapist decided he was not scary unempathetic (no cruelty to animals, etc.). I took him to the child psych b/c of the control battles. She told us to de-emphasize our authority and make it more universal. I think it sounds like T. is having control issues.
I haven't read those books about spirited or sensitive children so I can't comment. I need to. I think it could be possible for T. to be both. Are the books giving conflicting advice?
I believe Alfie Kohn and John Rosemond would advise parents of kids like T. not to feed the child's anxieties by justifying or indulging them. Act benignly unconcerned and kindly and mildly set a limit and stick to it. Rosemond would say, "If you want to cry and be upset about this, you must do it in your bedroom and not disturb the rest of us." (Rosemond is pretty snarky, but if you can get past that, it comes down to boundaries.)
Since being around other kids defuses some of T's anxiety, I think you need to use that as much as possible. It can be hard to set up playdates and go back and forth, and with the twins, this would complicate your nanny's job and divide her attention further. What about a regular, daily after-school program or a full-day program? I don't think a therapist is going to try to change this. I doubt if it's even possible. If being around other kids makes her behave better, the therapist is likely to advise you to find ways to make this happen.
DS was/is a talker, too, but it does taper off with time, esp. after they learn to read (assuming they enjoy reading).
Is T. getting enough exercise?
I know you've mentioned that dh has some mental health issues (OCD? bipolar? I don't remember). You could ask a ped. or a child psych when this begins to emerge in children and how to recognize it.
Gl. I understand how hard this is.
Keiki's Makuahine (Keiki's Mom) 50, dh 50
Keiki: b. 2002 after 3 months bedrest
Natural conception following ZIFT/chem. pg
Olivia: b. 1999 d. 1999
28-week preemie, ptl cause unknown
Natural conception after 1 mc
ttc since 1998