It sounds like your mom is very anxious and so she is worrying about all the possibilities. I work with a similar population that she does, and a lot of staff worry a lot about their own kids. Sometimes I think they probably overly analyze each move their kids make. That's part of the hazard of the job. You see the worst case scenario--which is not the reality.
My mom is a negative worrier, and so were the couple of generations of women before her. One time when I was 16, my mom actually complained about my pessimistic attitude. I thought it was pretty funny considering I had learned most of it from her. Plus, she was always creating disaster that we were always trying to recover from.
You can't change your mom. She will most likely stay the way she is. The only thing you can do is take steps to make your life better.