I'm not sure of your symmetry wrt your deltoid group (ant vs med, etc).
But, I can almost bet that your front delts are somewhat proportional to the rest of your body due to its incorporation in most pressing lifts. It's the side delt that is usually the trouble spot for most.
If this is the case, I would drop any and all shoulder presses. Your front delts should get plenty of work when bench pressing, dipping, etc. Concentrate on your side/rear delts and allow them to catch up.
I have had similar troubles developing my side delts. I did raises till I was blue in the face... dbs, cable etc. I found that I was lifting the weight, but not properly stimulating the side delts.
Try dropping the weight on your side laterals a bit. I dropped from 35 lbs to 20lbs. And dropped to 85! on upright rows.
Three things to try...
1.) don't come all the way down... your arms should stop anywhere from 45-30 deg from your sides. This keeps tension on the delts and doesn't give them a break (TUT).
2.) Don't bring the weights up much past your shoulders, if any. Your traps will become the primary mover at this point. Again, this is to keep tension on the delts and make them kick some a$$.
3.) Work with tempo. Try taking 2 seconds to raise the weight. PAUSE at the top for 3-4 seconds. Then take another 3-4 seconds lowering back down. This is the main reason for having to drop the weight. TUT is a b!tch.
When your arms get back to the 30 degree mark, lift them DBs back up... no rest.
The same goes for barbell upright rows. IMO, people chicken wing their arms way to far in the air, making a 'v' shape. We want to work the delts here, not the traps (unless you specifically want trap work, as well). Try similar things as mentioned above. Never stop, never come all the way down, slow and controlled, pausing at peak contraction.
I started utilizing these ideas (which are primarily based on the Time Under Tension - TUT - principles) and all of my lagging parts started blowing up... as well as my more dominant muscle groups... everything got better.
Just a thought...