The Doctor studies the face reflected in the mirror; it’s changed, unfamiliar, new, female, which is odd. The craggy face and grey hair are gone; this body is younger, shorter, and the wrong shape.
Being a Time Lord means becoming accustomed to changing face, body, even temperament and personality; that’s what regeneration does. Old body dying? Have a new one.
On one level, the changes aren’t a surprise, only the Doctor had never changed gender before to his… her knowledge. Always knew it was possible, but…
So here she is, new body, new parts, same old Doctor.
Still not ginger.