What Thomas Bertilson has said really. I have used the Kodak Xtol times for Neopan 1600 at EI 1600 and didn't find my negs thin. Try a print from your negs. Let us know how it goes. Do you get a sparkling print at say grade 3/3.5?

Unless you have used this combo of Xtol and Neopan 1600 before and are experienced with it then try printing and see what you get.

If I had to make any comment about what you did, I'd say that you should maybe try 8-10 initial agitations which will take more than 10 secs and then at least 3 agitations every 30 seconds. One inversion every 30 secs might not be enough BUT until you do Thomas' tests and then try printing you won't know what changes to make.