Pain Free Chair

I have just received my chair and love the way it sits, but when I try to attach myself to the backrest it seems to be too high and interferes with my shoulder blades and shoulder rolls. I am not a petite person, 5'6" with long arms and legs and a very short waist.

I have looked at the dimensions of both chairs and wonder if the petite back on the regular chair would fit me better. It was not suggested when I called for help choosing a chair. I see the total heights compared, but that doesn't tell me where the petite height is reduced, except for the 1" less height of the backrest itself. Is that even an option? Thanks very much.