Dauntless, I have the very staff you are looking at in SY. I use an adjustable coupler, which is about 4 inches long.
This is the staff, lit, standing next to a door. The room is 9' ceilings, for scale.
This is the staff, joined, no blades, with a dark initiate V3 lying next to it.
I use the 24" initiate blades in my staff. With the blades, it is almost exactly 6' tall.
My daughter is about your size, she has a staff which consists of a pair of Initiate V3s and a flush coupler. The center is quite a bit shorter, and in staff mode she has less reach, but I've found that I can wield 36" blades in her staff hilt fairly comfortably. That staff is a little long, however.
I would recommend a middle-ground. Get the Phantom Initiate V3 staff with an adjustable vented coupler. The center part of the staff will be a good 4 inches shorter, which will make it a little easier to wield and a lot more responsive.