it might also help if you could hexdump the MBR and show it to someone that knows how to read these things. You could also hexdump the GPT and backup GPT, and see if there are discrepancies, or if the data is completely done.
Potentially the drive may also have suffered a controller failure, and reports false data. What does SMART tell you?
I usually use the system rescue cd linux "distribution" to attempt such fixes. It's not exactly user friendly, but gives you almost all the tools you could ever need, including driver error logging, smart, hexdump, fdisk, dd_rescue und ddrescue...
It will not be able to recover the actual data, due to the encryption, but it should be able to determine what's left of the pools, how the MBR looks, and whether any hardware errors get thrown.