I just ordered this part from Germany. If you type the part number in Google there will be a German site around 2nd or 3rd on the list. Rockshox told me this is the correct part for a b type model fork. If yours is a b then go for it. I did exactly the same as you to start with and found the spring shorter. The part number 11.4018.010.165 is different and has that little bump spring on the bottom like the oem part. But make sure you have a B model fork first.

Here is the German site https://www.bike-components.de/en/RockShox/Ersatzfeder-fuer-XC-30-27-5-29-100-mm-ab-Modell-2016-p56811/

I just ordered this part from Bike-Components.de in Germany, which I found by Googling for the part number. Rockshox told me this is the correct part for a B-type model fork. If yours is a B then go for it. I did exactly the same as you to start with and found the spring shorter. The part number 11.4018.010.165 is different and has that little bump spring on the bottom like the oem part. But make sure you have a B model fork first.