Couple more suggestions....
I have used a video recorder placed out in front of me and the rifle, off to my right and mounted on a tripod (like the guys on Youtube do). It gave me the ability to see exactly what I was doing each time, vs what I thought I was doing. I could review and analyze later. It was a good tool for me. Could see subtle position and method changes. Could see whether the bipod hopped and which direction. Even discovered that I blinked a lot. LOL
I also find it hard to shoot any lightweight rifle, with any amount of recoil, using the free recoil method. IMO free recoil is for heavy bench rifles. A light rifle needs to be controlled somewhat. I would try pulling the rifle into my shoulder and using a tighter grip on the stock. Maybe even controlling the forearm with the left hand. Just need to find what works the best consistently.
Finally, IMO there is a very small difference between a flinch and a startle. So small that they may be indistinguishable. I would try the old trick of having a friend load the rifle for you, while you are not looking, and at some point leave the rifle empty, without you knowing. You will know if you are flinching when you pull the trigger on an empty chamber. Even more decisive, if you have it on video. Good luck.