Welcome to the forum and congratulations on your efforts so far. In order to give good specific advice, it will be necessary to have details on your airplane. Is it built from a kit? Is it built from a plan that is available on the internet? Please give all dimensions and specs, including: weight overall with propeller and without rubber motor, wing span & chord, Stab span and chord, wing weight, stab weight, dimensions of wing and stab components (leading edge material, trailing edge material, rib material), motor stick dimensions & weight, tailboom dimensions & weight, propeller weight, fin (if any) weight, Propeller type & pitch & propeller thrust bearing type, wing & stab airfoil, wingpost length, thrustline offset, tailboom &/or rudder offset, stabilizer tilt, wing offset, left wing washin (if any), rubber motor length and thickness and weight (and what types of o-rings, if any), center of gravity location (with motor installed, distance from the wing trailing edge.
Also, describe your rubber motor winding technique, flying specs and procedures and describe your current flights in detail.
The first step in trimming is to know all of the above and have all the built-in settings in a reasonable range.