The way my shock is, there seems to only be 4 positions but then there seems to also be a whole other adjustment section on the other side but it's impossible to get to.
Look at the picture below as I explain this.
When you adjust the "preload", what you're doing is adjusting the location of the bottom of the spring on the shock body. The only part that moves is the silver notched ring that the spring sits on. Since nothing is holding the bike up or down, the top of the spring will always be the same height above the bottom of the spring, unless you change the weight on the bike.
You change the spring height to keep the shock travel in the same range of motion as you compensate for changes in weight. The unloaded ride height changes as you adjust the spring, but the loaded height is supposed to be the same with changing load weight. When you add weight, you raise the bottom of the spring; when you shed weight, you lower it.
There are not two separate height-adjustment ranges. See the metal oval welded to the shock body that the stepped ring rests on? There is a second one on the opposite side just to make the load equal around the shock, and there is a second set of steps that rest on that second oval. The whole ring moves up and down with two sets of steps resting on two ovals.
The picture below shows this shock is set to the lowest position, corresponding to be adjusted to carry the least weight, because the spring will deflect the least. Notice that the ring can only be rotated in one direction, because of the great step stopping it from going the other way. You could rotate it up the steps and drop over the big step if you wanted to.
If you were to do that, rotate the ring a full 180 degrees, and over the big step, you'd be back exactly where you are now, the only difference being you'd see the side of the ring that usually faces the wheel. It's the number of step "landings", not the number of step "risers", that determines the number of ride-height adjustments you have.