It would be technically possible to adopt from foster care and specify that you will only accept a child with no physical or neurological differences. But realistically, most children available from adoption from foster care will have SOME significant issues, if not present from birth, then the result of a dysfunctional early childhood and years in and out of foster care.
And of course, there is no guarantee that a child won't develop a disability or 'special need' later. All it takes is one serious accident or illness, and you have a child who can't walk or can't see or is mentally disabled. A little bad luck and your child is diagnosed with leukemia or osteosarcoma or a brain tumor. Can you afford THAT? Can you handle THAT?
Being a single parent is tough, and takes more money than if you were married. Is there some rush to become a parent NOW?