You are 21 years old now. How about looking for a job, saving money and gaining some independence? If you are dis, look for facilities for those so challenged.
Most of the folks our age aren’t looking for our kids to care for us. We hope we aren’t needed to care for our kids even in our old age. I think you should be thinking more about YOUR future than your mother’s. She’s got a life, a job, money, a SO. YOU are a problem to her.