I think what vkashi meant was to make the exposure darker for a more dramatic efx on its atmosphere/climax.
Symetrically and graphically the exposure was well composed and it shows lotsa of different tonal efx. But one thing you have to be careful when converting to B&W in PS i.e. if you converted by changing the color mode to Grayscale or worst of all, Desaturate, the latter will cast a red tinted tone on yr image. Once in Grayscale mode, lotsa of tonal details are lost.
One technique you can use is playing with layers and layer-masking to retouch or tonal-correct certain areas. Techniques like doging & burning are essential in B&W traditional darkroom and therefore the same technique applies to digital darkroom too.
You can burn-in the bottom part of the exposure, probably half of it. At the same time keep the whole appearance as natural as possible. I presume you converted this exposure using Channel Mixer, in which you have more controls and get accurate conversion. Based on yr case, after studying individual color channel (RGB) for its mid-tones, highlights & shadow details I'll convert to B&W in Channel Mixer, then study its Histograms and adjust its Level. Followed by dodging and/or burning to yr desired result.
Well you might think this take a longer time than you expect. In B&W photography & post-processing (or the traditional darkroom phrase, printing), you gotta have discipline & patience and being critical in detials, in order to produce a great B&W photograph.
Hope these advices help you in anyway. Cheers mate!