I am so sorry you are having to go through all of this. Unfortunatly, I do not have the personal experience of dealing with the beurocratic red tape. I do have a website that I found that may be able to give you and your doctors a little insight. Hopefully, they can get a better understand of what exactly they are looking for. I would recommend reading this site, then maybe even printing it off and talking with your doctor about it.
http://www.marthachurchill.com/ssmibasic.htm
This is apparently from a lawyer who specializes in Mental Health cases for people applying for SSI or SSDI. Hope it Helps.