More weights in the shoulders will definitely help, but examine the rest of your gear configuration, too.
For instance, I usually dive mine with the stock 28 cf blue football cylinder, and I run two pounds in each shoulder. I sometimes use a 50 cf when on a trip or a liveaboard where I've got to partial pressure blend my cylinder, to avoid the annoyance. I move just one more pound to each shoulder to balance out the weight, but I add a little more to the waist to account for finishing up an aluminum cylinder at 300 psi. All my diving is drysuit, so with thirty pounds of lead, I've got a bit to move around. On the other hand, a pound here and there can make a significant difference. Moving to five in each shoulder is a LOT of weight to move up there, and seems particularly high for a Dolphin...
Look at what you have clipped where on the BC - do you dive a cannister light or clip on lights? Can you move them higher up towards your shoulders? Argon for drysuit inflation? Can you mount the pony higher? (or do you dive wet?) The way you mount your bailout bottle can affect your center of gravity - do you mount it to the unit, or do you side sling it like a stage? Have you considered moving it up higher on the side of the shell?
When I first started diving the Dolphin, buoyancy and trim were a problem, too. The number one improvement I made was throwing away the ankle weights I'd been using since learning to dive... They were totally unnecessary and were the greatest impediment to being level I'd ever seen; without them, things instantly got significantly better.