Possible roadblock

On Sunday I took part in a chat with publisher Elizabeth Law. It was a fantastic and very illuminating experience, and answered many of the questions I had. Unfortunately, one of the answers I got has thrown me into doubt as to whether I'm pitching my novel correctly.

In Assignment 9, the protagonist, Casey, is 18. Apparently 18 is too old for a YA protagonist. In the parallel story, Casey is 10. Too young for a YA protagonist. So where does my book fit? At a pinch I could make her 17 in the 'NOW' sections, but it would not really work - not a lot of 17 year-olds are at university. And no, I can't make the university a boarding school because she has a brother 4 years older who is a big part of the plot and he wouldn't be at boarding school.

It's not an MG book, despite the 10-year-old. The themes are too adult for that. Yet it is not an adult book either. I'm not quite sure what to do now, because it seems I have written something that is completely outside the lines. And it was completely unintentional. In my mind, this is a YA book. It has always been a YA book. The voice, language and themes are all geared for a YA audience. Assignment 9 is a book I would have loved as a 14, 15, or 16 year old.

I'm completely flummoxed as to what to do. Perhaps this is the reason I have not gotten far with my queries to agents...