You are using your knuckle, and usually to the right of the flag, then moving up or down as required. From that knowledge, the chances are you will normally find a point to aim your knuckle at, that is at some point above and right of the flag.
The advantage of a sight, I found, is that I could choose a very clear point to aim at, before the sighters started. In your case, you might choose a nice clear point to aim your knuckle at.( above and to the right of the flag.)
Then after sighters, you might have to aim lower or higher etc, but perhaps at something not so clear as the first point of aim. With a sight, I could choose a clear point and adjust the sight to continue using that same clear point.
The other thing with a sight is that after sighters, if my arrows were 5m short; I knew how much sight adjustment was needed to move them that far up the field. Getting to the flag in the first scoring end is a big advantage....