Your substrate is too thick up front. You don’t need it that deep plus it takes away from the height.
Take some inspiration from your wall art.
See the near and the far away rock? It looks like they’re miles away from each other...
Move the big rocks to the front and the smaller ones behind them but higher up on the slope.
I’d also play with the orientation of the peaks. It would make it more interesting if they’re pointing at each other from left to right and vice versa.