That is awesome. Keep working on it.
A number of years ago Marty Rueter explained to me some concepts of hammerstone thinning, that I have found to be invaluable.
You can see some of his videos here, including hammerstone videos:
https://www.youtube.com/user/Flintknappingtips/videosAlso, depending on your grade of stone, you can thin with hammerstones for quite some time.
Before learning from Marty, I used hammerstones for spalling and trimming. Then, I cooked the stone after the trim, and finished the pieces with small whitetail batons, that were fairly light. At that time, I could not work the stone raw.
Anyway, what Marty showed me was the process of chipping in a "platform", flipping the stone, and then striking against the platform with a hammerstone.
There are many ways that this can be done. There are different kinds of platforms, and different kinds of hammerstones, and even different kinds of hammerstone materials.
Anyway, if you are working on learning to thin, I would recommend watching every good hammerstone thinning video that you can find. What you will see is that the better knappers are actually going through a process.
