Sorry to hear about your symptoms. Visuospatial problems, cognitive changes and hallucinations in a previously high-functioning individual are concerning for a progressive dementia caused by neurodegenerative diseases such as Lewy Body disease (usually has some parkinsonian features also), Pick's disease, ALzheimer's , etc... or infection such as herpes simplex virus or prion disease. Prions are abnormal proteins that have been linked to diseases such as mad cow disease and Creuzfeldt Jakob disease in which there is a rapidly progressive dementia (yours sounds too slow). This as well as herpes can be checked with spinal fluid samples. Finally there are paraneoplastic disorders that can cause behavioral and cognitive abnormalities in the setting of a hidden cancer through an autoimmune process, but again the progression of your disease is slower than that reported with paraneoplastic disease.
What is particularly concerning is your abnormal EEG that showed the diffuse slowing and ?possible Rt sided lesion inthe temporal lobe (could be non specific change). This again points to a dementia like picture. It sounds like all the right tests have been done so far, but I would repeat the EEG to look at the degree of slowing present and the right temporal region again. Observation and serial neurological exams will be important in making the correct diagnosis. PET scans to look at metabolism in different parts of your brain may also be of help. Consider a behavioural neurologist for a second opinion. There are excellendt specialists at U Penn, UCLA,and U Florida if you are in the region. Otherwise followup with a neurologist that you trust. Best of luck