try changing out your routine, start out with rear delts supersetted with plate raises (take a 45 raise from blow chest level to over head using straight arms) as many times as you can, then move into just less than shoulders width upright rows, finish off with presses, if not enough alternate presses with heavy upright shoulder flies. ( seated upright, use dumbells in a fly motion to only work shoulders, focus on contraction.) keep your rest times down, no more than a minute and a half. you gotta push your shoulder to work, also it is sometimes very hard to isolate shoulders, so maybe lighten the weight a little just to ensure you are hitting your delts and not using pecs or traps to help.
~yoked