Interesting that you had Numbers quoted at all. I had to ask and still only got replies from one clinic about it, the others sort of said it depends and we will see...
Now you can try to simulate or let other simulate jaw change on your photos, maybe use VFFS as a starting point and see if you already like that simulation or if you want something changed. Then you can go and ask a surgeon how much mm that would be to reach that goal.
2mm are a subtle change indeed. Facialteam does a few of these subtle jaw changes and I know a lot of people are happy with it , while a few wanted a revision because it was too subtle for them. 10 mm is very strong change, almost like what they do in Korea. This can have impact on the function - taking off too much can endanger the nerves, the stability of the jawbone or the muscles and glands attached to it. Also depending on your age, 10mm will probably cause skin sagging and then you need a lower face and neck lift later. I would either push the ones who said 2mm to do some more, if they are willing to do that, or tell the one doing the 10mm to be more careful and maybe do a little less..
Part of how much can be removed depends on the position of the mental nerve, which can be estimated from X-Rays or CT scans.