Id go with more volume brother. 15 sets for the upper back, total, atleast. The back is a large and stubborn group of muscles that needs to be thouroughly torn up IMO. Id add some barbell or dumbell rows, possibly both, some T-bar rows are great also. Conventional deadlifts instead of Stiff Legs, since those hit the hams more. Id also go with some wide-grip lat pulldowns as well. The main thing is to go for 15 hard sets to failure and use a good variety of exercises. The 12-15 rep range works well for me with upper back work. Id also do seperate work for the traps. You can do traps and lower back at the end of your back routine if you like. I train my lower back much like my abs. Weighted, and multiple times per week. Weighted hypers, and weighted ab work for the lower back and abs. Traps you can hit a few times a week, but if you hit them hard once a week that should help you make some improvements. Maybe 4-6 sets. More if they are a priority. These things are what have worked for me. Your body should adjust to the workload over time. Hope that helps