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)
Code:
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.