Because you did your drawing in the lower left quadrant you have set it to be all - (Minus) values so will work the wrong way round.
Do your drawing in the top left quadrant as per the image below and check the attached bccd file where I have re-done it in the positive.
Now working from the outside diameter of the stock towards the centre (X0) will be reducing numbers and moving out from the centre will be positive numbers.
Don`t worry that the drawing looks to be for a slant bed lathe it doesn`t matter, the numbers will work the right way for you.
You have to remember that on the slant bed the tool is upside down compared to a traditional front toolpost but the slant bed is only the normal toolpost rotated around the Z axis so is in effect exactly the same!! Nothing magical about it to learn
Hope that helps