I am querying agents and I would like to make an effort to target
agents that will represent my type of book. The problem is, I'm not
sure what to call it.
What's the difference between children's, middle-grades, and young
I've been describing my book as young adult, but I believe that it
will more likely appeal to readers in the 9-12 range? It's 65,000
words and is kind of similar to City of Ember.
Am I worrying about nothing or is a correct genre description
65,000 words is definitely going to be in the JA range unless you've specifically written it to younger children, which is a bad idea. The spectrum of children's literature is very well-defined by publishers based on age and mental maturity. 2-4-year-old books are largely picture books with extremely basic plots. 4-6 you can start getting into more complex ideas like morality, lessons, mythology, and you have more text to the pictures. This is also the age that kids might be reading instead of being read-to by the parent, so you have to be strict on content. This is also the age when "special topics" books begin (like books discussing gay parents, divorce, death, illness, and even abuse and incest. The only topic completely off-limits is abortion, which is not allowed until YA). By middle school, the pictures are cut down to minimum and the children are assumed to be reading on their own, but certain topics are still off-limits except if handled in a very gentle manner, hiding behind imagery. The word count is still relatively short because of attention span, but much larger than picture books. (Kids do read ultra-long Harry Potter books in middle school but this is a special case). YA applies generally to kids in 4-6th grades and is when the topics open up to things teenagers deal with, like sexuality, death, self-image, suicide, anger, etc. It really ends at around age 12-14, when kids generally move into adult books. I remember reading Jurassic Park in sixth grade, which was my first "adult" book, and I was the only one reading that kind of book in my class. By the end of 7th, everyone was reading adult books. (Actually, they were mainly reading magazines and listening to music)
It seems like you have a standard YA fantasy. Anything below YA (Young Adult) should be written with a lot of research into what are the acceptable limts to the content and you should specify the grade range.