So your date last insured is in the past. You are right that appealing it up the ladder is the only way to keep your SSDI claim alive.

Another option you may not have considered would be to work a little for the next five years, earning $5000-$6000 a year so you get additional 20 credits so you have a new date last insured. That would involve working about 12 hours a week at $10 per hour to make about $500 a month. Not substantial gainful activity. File another claim in 2016. See your doctor regularly. Keep your own copies of medical records.

Obviously, I don't know your mental or physical limitations, so I can't tell you what kind of work you could do.