Neurology is a medical specialty that concentrates on finding a location in the nervous system to explain medical symptoms. Determining one anatomic location to explain all of your symptoms is difficult. In these instances trying to localize one major symptom is a reasonable step. Left sided weakness in the leg (only) may be from a problem in the spinal nerve root, spinal cord, brainstem or brain. Imaging with MRI and a test called an EMG/NCV will help. If your weakness also involves the arm, an EMG/NCV and spinal imaging below the neck is not needed. Spasticity suggests an increase tone in the limbs, and is associated with what we call an “upper motor neuron” problem. These tests will also help with that. I do not put much importance on the increased reflexes - unless they are greater on one side than the other, and numbness is not something that really helps with a work-up. Your doctors may wish to do a spinal tap.
The bladder dysfunction you describe usually requires both sides of the brain to be involved, so successful treatment is more likely to be found with a urologist. Ask for a referral.
Sexual dysfunction and a slight tremor are more likely to be a result of stress from your medical problems or other factors.
Intermittent double vision would occur from a rare disorder that does not fit with your other symptoms. Ask your neurologists if they have ruled out Myasthenia Gravis. I am confident they have done so.
Please know, that if all of this has been done, it is likely that there will not be an easy diagnosis. Also, please know that I do not wish to offend you or any other reader, but in some cases these multiple, unexplainable neurological symptoms stem from childhood abuse. If this is the case I am sorry, but it is important to discuss this with your family and your doctors. You have no blame for those incidents. If there are none of these issues, it may still be a stress related illness, and it is important to ask your doctors if they think this is the case.