Looking over the modules that the OP said are loading, I don't see the b43 driver module being loaded. If the b43 driver isn't loaded there is no system call for firmware to be loaded, then there also is no firmware error.

I would first start by loading the module (as root)
modprobe b43
If it returns with no errors, run the dmesg command again, look for messages that it detects the wireless and tries to load firmware.