You claimed 31000 new nurses plus 19000 existing nurse equals 50000 new nurses. I pointed out that is 31000 new nurses.
Now you are arguing that it's not the number of new nurses, but how many there are in total. I agree that more nurses is better. But you have changed the argument away there being 50000 new nurses.
To be fair, the Tory Manifesto did say 'more nurses', not 'new nurses'.