I am currently recieving sis/ssdi for a neurological condition/learning disabilities. Although my onset dated was listed by SSA as later after the age of 22. the last year I worked , was the year I was 22 since my birthday was in late December the previous year. The year I was 22 My earnings were 4,856 for the whole year. 2009. so no sustained SGA , at-least not over 6 months if at all. all of my work history before there were relativly short attempts not lasting more than 6 months before ended because of my disability.
I recently obtained a letter from my pediatrician neurologist that originally diagnosed me with my disabilities as a small child back in the 90s and I sent the letter certified to social security. do you think this would help my case ? or do you happen to have any recommendations for me to improve my chances of approval ? i've been very anxious about this.

Hi. My answer assumes that you've applied for disabled adult child's (DAC) benefits, since that's the only type of Social Security benefit that requires a person's disability to have begun prior to age 22.

Any medical evidence that you make available to Social Security that documents that your condition(s) became disabling prior to age 22 could potentially be helpful. In addition to being medically disabled since prior to age 22, though, in order to be able to qualify for DAC benefits you can't have done any work that Social Security would define as substantial gainful activity (SGA) since turning age 22.

The monthly SGA limit in 2009 was $980 for non-blind individuals, so if you earned more than that in any month after your 22nd birthday then it could present a problem. However, even if you did earn more than the SGA in some months after reaching age 22, it may not prevent you from qualifying for DAC benefits if Social Security classifies the work as an unsuccessful work attempt (https://secure.ssa.gov/apps10/poms.nsf/lnx/0411010145). Assuming that you are in fact applying for DAC benefits, then you'll want to tell Social Security about any work that you did after turning age 22, including any details that explain why you believe the work was not SGA.

Best, Jerry