What type of weight are you doing for deads and squats? How often do you do them? Just curious.
The more heavy lifting you do, when it comes to lifts like squats and deads and such, your 'trunk' will grow.....given that you are increasing the weight that you are doing.
Look at a lot of PLers and strongmen. They core/trunk grows out of necessity. Now these are extreme examples cuz these guys are pushing some major weight. So if you are doing moderate amount of weight, then theres a chance that you're trunk area will not grow much. Once you start squatting in the 400's for reps, and DLing 500's for reps, your core/trunk area will be forced to grow.