First things first, the best way to get "more shape" in your abs is to drop bodyfat. Your profile says you're 5'10", 180, and 10% bodyfat. That's pretty lean for sure, but shaving off some more fat will get your abs to "pop" more. Can you toss up a current pic for reference?
The weighted ab work you're doing will help build muscle, but bodyfat is pretty much the be-all, end-all determination of how good your abs end up looking.
The rectus abdominus is one muscle, so there's no way to work one "side" and not the other. It's not like the biceps that do have two heads and respond slightly differently to different exercises. However, there are a few other muscles in the "upper ab area" (the external obliques or even the serratus) that you could be involving. Those are located on each side and can be focused on with twisting.
Flexion (crunch variations), rotation (twisting variations), anti-flexion (plank variations), and anti-rotation (Pallof press variations). Addressing those throughout the week should have you covered.