I had the same similar thing when I went into nursing. I worked with special needs kids in a clinic for about 3 year, and totally fell in love!!!
I live in the Atlanta area, and our children's hospital as the Marcus Autism Center that would be a good resource. I say this because I'm sure if you did a little research, you should be able to find something in your area that's about the same
Also, I would ask you to think about this..... you may like those types of children because it's the only thing you have been around... but you may have the ability to care for other kids of special needs children in the nursing setting. Children with cancer? Well, they are a special kind of kid. Children who need new organs? Or just children that have just got diagnosed with sickle cell. I would think that the reasons why you love autistic children can be the same reason why you like working with other types of children as well.
That's what I have learned on my journey into pediatrics (which I have an interview for next week after doing ER for a bit). I hope this helps.
Here's a link to the Marcus Center http://www.marcus.org/