If I'm understanding your issue correctly, you might want to try changing the verticalPageSize in the inspector to a smaller number, because according to the Unity Documentation found on Scroll Views here:

This property is controlling the scrolling speed of the vertical scroller.

This should mean that if you change this to a smaller number, the Scroll View's jumps should not be as large.

If I'm understanding your issue correctly, you might want to try changing the scrollSensitivity in the inspector to a smaller number, because according to the Unity Documentation found on ScrollRects here:

[This controls] the sensitivity to scroll wheel and track pad events.

This should mean that if you change this to a smaller number, the ScrollRect's jumps should not be as large, due to decreased sensitivity.