The C/G sounds about right, as long as forward flight has no stalling or diving.
If you think the C/G should be aft, begin by slightly moving contents or adding weight aft. As long as there isn't any stalling you should be OK. C/G is usually in the 28% to 33% range of the mean aerodynamic chord behind the center leading edge. Look at the plans, what C/G is called for?
Much, but not all, of the rules that apply to full size aircraft apply to our smaller ones. Don't take text as gospel.
Getting the C/G right will benefit you with longer flight times and be easier to control. There is a saying to keep in mind, "An aircraft with a too far forward center of gravity flies poorly, one with a too far aft C/G flies once."
Building and flying R/C since 1965