This has been bothering me after watching episode 1 again... why didn't the Doctor know she was now a woman? I've googled this and there doesn't seem to be any reference to this answer. After having been a man for 12 (13 including War Doctor) incarnations, wouldn't you know that you don't have male parts or even that you now have something hanging off your chest? (cos I'm sure that 12 wasn't wearing a bra) Wouldn't this indicate some sort of change, different to previous regenerations?
...and yes, I know the Doctor is an alien and therefore he/she may be different to humans, but to my understanding of Doctor Who (correct me if I'm wrong) - the only difference physically between humans and Time Lords is that they have two hearts.
It just seemed weird that when Yaz said "you're a woman" on the train, the Doctor seemed shocked/surprised but physically the Doctor would've realised that something was different after the regeneration. This is especially reinforced when the Doctor says something like she was an old man before.