This is a little more complicated than I anticipated. There is not a perfect solution here. I can tell you that if I saw you in clinic I would try a hearing aid in both ears to begin with. Even though you do not have any usable high frequency hearing in the left ear you have alot of low frequency hearing that can be aided and used to its full potential. Even though it might not add alot to your ability to understand speech directly - it can help with feeling “balanced” and will improve your ability to tell where sounds are coming from which can improve hearing in noise. When you are in noise, a very important cue from our brain is the ability to hear from both sides. Even in the realm of speech understanding your left ear would still be able to pick up alot of sound - when you combine this with your right ear then the improvement can be significant. Hearing is not additive; for example if you understood 10% of speech with your left ear and 40 percent with your right ear we would not expect you to get 50% when you listen from both sides; it is more likely that you would improve much more than that. In the world of sound, even a small improvement can result in a huge functional improvement. Especially when you add in other cues from the real world such as speechreading/lip reading, using context to help.
There is a hierarchy when it comes to using sound. Best case scenario is you are able to comprehend what you are hearing (e.g. understand what someone has said). Below comprehension on the hierarchy is discrimination - the ability to be able to determine what the sound is or discriminate between two competing sounds. Below that is sound awareness - the ability to be aware that a sound is present even if you aren’t able to discriminate what it is. Even if the hearing aid in your left ear was marginal in its improvement for speech understanding it should help with your ability to discriminate and be aware of certain sounds.
With 12% word recognition our expectations for comprehension in your left ear are poor - this is most likely why the Audiologist recommended a CROS because in his/her opinion they did not believe there is benefit to be gained. This is a possibility; but I would not make this conclusion without trying because th decision to abandon an ear is a very significant decision. Your hearing in your left ear will never be as good as your right ear due to the nature of your hearing loss, but there is alot of usable/aidable hearing in your left ear to at least TRY and work with (i.e. a trial with two hearing aids). Moving to a CROS/BiCROS system is your way of telling your body that you no longer are interested in keeping your left ear active/healthy and there is a high risk of the auditory pathways/nerves wearing away.
I would not recommend a CROS/BiCROS system unless I knew you had an accurate trial of two hearing aids and we determined that you were receiving no benefit form the left ear.
If the Audiologist you saw is not interested in trying two hearing aids with you and only wants to go to a CROS/BiCROS then I would find an Audiologist who is interested in trying. The outcome with hearing aids is unknown because there are so many aspects of your hearing loss that cannot be determined from an audiogram. It is also going to take quite a bit of time, most likely, for your to adapt and use the hearing in both ears to their fullest potential, especially the left. If you go in with the mindset that this is rehabilitation and it is going to take time then you’ll be better prepared to tackle this process.