Have you mailed it yet? If not, than I would suggest you call your local SS office and ask for a replacement. I believe they send out another copy if you fail to respond as well.
Getting the long form isn't ideal, but if you are still receiving medical care and your condition hasn't improved, you will likely not have a problem, but it is more work.
You saw this link?
http://nymakesworkpay.org/docs/Guide_CDR.pdf