You are probably receiving Supplemental Security Income (SSI) rather than Social Security Disability Insurance since SSDI is paid to people who have worked enough years and then can't work any longer. SSI is not just a disability program. It is a low income disability program and when you were under age 18, you had to be found disabled using the childhood rules AND your parents had to have low income and resources.

If it is SSI, at age 18, your disability will be re-evaluated under adult criteria AND your parents' money will no longer make a difference in payment. Where you live, who you live with, whether or not you are married, how much savings you have etc. will determine how much SSI you can get.

It is possible that you were getting survivor or dependent Social Security benefits if one of your parents were deceased, disabled or over 62 and retired. Then, you qualified only because you were under age 18. Those benefits can continue if you are found disabled before age 22 and are unmarried (some marriage exceptions).

It is important that you understand the benefits that are being paid on your behalf. Talk to your payee. Read the letters.