If you follow the current timeline, it should go-
Hurt->Eccleston->Tennant->Tennant->Smith->Capaldi->Whitaker->Tennant->Tennant/Gatwa
Hurt was the real 9th doctor, but we call Eccleston the 9th doctor. And (if I get this all right) Tennant regenerated as himself twice, so he should be the 11th, 12th, 15th and Doctor 16 and a half. But people call him the 10th doctor. And Jodie Whitaker should have been the 14th Doctor, but people call her the 13th Doctor. And then Tennant came back and then there was the bigeneration of him and Gatwa.
And just to add to it all, there’s also a female clone of Tennant out there somewhere.
Is anyone else as confused as I am?
EDIT: Oh god, I just realized it gets even more confusing because now there’s all the Doctors before Hartnell.
As far as I understand it, Gatwa is the Fifteenth with the “second Tennant” Doctor being the Fourteenth (distinct from the Tenth). To add even more fun to this, it’s been implied that 15 technically comes from a point in the future of the Doctor’s personal time line (“we do rehab out of order”) and 14 will properly regenerate into 15 when he has healed his mental and emotional wounds.
Regarding the “Hurt” Doctor, he ‘temporarily’ discarded the name of the Doctor during the Time War, reclaiming the name “the Doctor” afterwards (hence Eccleston being the 9th). The official name of the Hurt Doctor is “the War Doctor”.
As far as confusion, eh it comes with the territory. At this point I let the BBC sort it out 😊