The way I'm seeing the scratches in your photo, most of the thinning seems to be going on higher up the blade face. I'm not seeing many scratches right near the edge.
Give the marker trick a try. This'll help you see where your scratches are.
There's more than one type of thinning, too... (1) Thinning behind the edge and (2) general thinning.
(1) You'll want to remove metal from as close to the edge as possible, as this is where the edge gets thicker over time due to repeated sharpenings. Think of this like maintenance thinning. Keep the spine off the stone.
(2) This said, there's also nothing wrong going for much more aggressive: thinning--removing metal from behind the edge all the way up half (or two thirds) of the blade face, if you're trying to thin the knife out more in general. Basically lay the knife flat (or close to it) and see what's happening.
Regardless of what you're after, more scratches would help
This shows (1) Thinning behind the edge and (2) general thinning. Red lines help show angles.