Unless you cannot reach the trigger don't worry too much about LOP. If you are trying to determine point of aim, this has nothing to do with patterning, TAKE THE BEAD OFF YOUR GUN and follow the steps above. Remember your eye is the rear sight, so to raise the point of impact raise your eye, to lower it you must lower your eye. Unless your are extremely tall, with a Remington factory field stock, I doubt you will need to lower your eye. To raise it tape some 4x6 pieces of cardboard to the comb. If this works you can buy a neoprene sleeve with different inserts. You can adjust pitch with a quarter or two under the recoil pad then buy and grind to fit pitch plate from Midway. Pitch is fine tuning and not necessary for the beginner.
IMO you are worrying too much about gun fit. Close is good enough to start, and with only 700 rounds under your belt, that is where you are. Get your gun shooting where you look then go bust targets.
FWIW we had the South Carolina Youth Shooting Foundation State Sporting Clays Championship this past weekend. 386 shooters attended.The winning 3 man varsity squad missed a total of 12 targets out of 300. Their top shooter had a 99/100. All with stock Beretta 391's. Other than drop adjustment, they were as they came out of the box. A custom fit gun is nice, but not necessary.