your needs don't seem to be in excess of wht theSSA requests.
here's the link for info required if filing online
if you have filed tax returns the SSA admin should have the info the the 2 years required
https://www.ssa.gov/hlp/radr/10/ovw001-checklist.pdf
if you are making a visit to SSA to sign up here's the checklist
https://www.ssa.gov/disability/Documents/Checklist%20-%20Adult.pdf
and here's the other medical and job worksheet
https://www.ssa.gov/disability/Documents/SSA-3381.pdf
if you used Turbo Tax online you can print the 5 years of return for a fee
or
if you used desktop and save the .tax20xx files or pdf's of them you can print them out for free
or
you can use IRS form 4506 to request copies of the returns - don't know if transcripts would be adequate thry can be obtained thru an online request or by filing form 4506-t.
