It looks to me like the focal point of your current layout is the grouping of three rocks right next to each other with the tallest rock in the center.
The cluster of hair grass in the background on the left side of the tank also draws the eye in.
Maybe for a test you could move the group of three rocks to the left side of the tank (measure 9" in to the tank from the left hand wall of the tank and center the middle rock of the group on that location).
This will take the focal point that is the rock cluster and position it according to the Golden Ratio and it will also allow the hair grass to sort of 'backdrop' the rock cluster.
In theory this will allow the hair grass to add emphasis and impact to the rock cluster that you are using as a focal point rather than distracting from it.
Once you get the focal point figured out in a way that you like then you can attempt to add the remaining rocks back into the aquascape in a way that doesn't 'break' the layout.
Basically start with a good focal point or centerpiece (though it won't actually be centered) to form the core of the design and then everything that you add after that should compliment the focal point rather than distracting or detracting from it.
Hope that helps.