Mr. Valenzo:
If it is ok to ask, where are you located? I think a competent bass luthier could adjust your custom bass to produce more sound.
I am too far away to offer any help, but I suspect it could be improved.
I make very powerful five-string fiddles, but the five-string bass I built last summer did not have as big a voice as I hoped.
Hope you find what you want.
Chet Bishop