You really are in a tough spot. I would have your doctor call the Social Security case manager and explain your situation. The doc may be able to present your parents uncooperativeness in a more convincing light. I noticed in your profile that you sometimes volunteer places. Do you feel comfortable enough with any of those people, who would see your limitations and possibly testify to your inability to provide consistent service in a regular work environment?

I would definitely get your doctor or another clinician on board and have them try to intervene.