What age group are we in

Hi, when we go to worlds I was wondering what age group we would be in.

In the Uk championships age groups were not seperated, there were teams from years 6 to 13.

We are in year nine or grade 8 in America, does this mean we will be in middle school?

Or are we not because we qualified by beating six formers?

Thanks for your help

Tall668 EBS