What Can Be Done for Chronic Pain/numbness 2 Years After Liposuction and Arm Lift?

I am sorry to hear of your troubles. It sounds like you had a nerve injury. These are rare, but characterized after arm lift surgery. Pain management doctors might be able to get that under control for you. They are generally anesthesiologists. Ask your surgeon for a referral.
Best Regards.

The finding you report Left side numbness lasting 2 years"...my left side from the waist to the foot was numb" is VERY atypical and I have not seen it.
I ASSUME you have seen a neurologist and had a CT. In my experience it is seen in only 2 scenarios a massive stroke (which would have most likely left you with muscle weakness on the right side of your body - HEMIPLEGIA and inability to speak, Dysarthria) or in certain psychiatric stress conditions, such as CONVERSION REACTION. The latter is seen with Post-Traumatic Stress Syndrome and other similar conditions and while VERY real to the patient, does not have any CT / MRI findings nor follows any known neuro anatomical pattern.
If everything was ruled out, you may want to consult a psychiatrist who specializes with such disorders. You may find your symptoms could be reversed with hypnosis, relaxation therapy or even some medications.
Good Luck.