That is the point of Social Security, some are disabled to start with, and if you have ever worked and paid in anything, and become disabled, you are in for Social Security, not SSI.
It pays better, and has a higher asset, income cap. It was something like under 24 or 26, and you qualify.
Still, expect it to take a few years and an appeal or two.
Go read the law online, from what you say, Social Security is for you.
You will have to supply medical documentation that your condition is untreatable, will last for more than a year, and they will want you to see their doctors.
All cases seem to be rejected to start with, appeals are needed. Expect it to take time.