To gap shoot you should not be focused on the arrow or the arrow point. You should be focused on the spot you want to hit, with the arrow or the arrow point in your out of focus peripheral vision. If your focus shifts to the arrow or the arrow point, you should let down and start again. It does not really matter if you can see the arrow point or not. If you can't see the point, use the furtherest point you can on the arrow shaft to aim the shot. As long as that is consistent, it should be accurate. I think from your description, you are using a very high anchor point, which is probably why you can’t see the arrow point.
Normally, the longer the arrow, the closer the point on. However, if your arrow nock is right up by your eye, that would sort of negate the effect of arrow length, because all of the arrow length would be compressed in your vision to an insignificant length, which probably also explains why you seem to have a variable point on distance. Normally, there is only one point on distance for any given setup.
Your setup is so far out of the norm that I really can’t help you, except to try and describe what is going on. If you are happy with it, fine. If you want a more typical setup, pick an anchor that is low enough so that you can see the point of the arrow, and then don’t focus on it. I once shot against someone in a tournament who was using a high anchor like that, and since he was beating me, I tried to duplicate it. But I never could get any good at it, so I want back to the usual anchor for gap shooting, which is low enough so that you can see the arrow point.