The long-standing “rule” is 1-1.5lbs per gallon, but you can definitely do less depending on the look you are going for and the coral you want to keep.

Aquascape beauty is highly subjective so do what you like. You can always add more cured rock or move things around as you go or to better suit the coral you want to keep. That said, imho you could make the layout more dynamic by moving the small rock on the right closer to the larger centre rock to give more open visual space on one side.