Translation:Didn't you already go to seventh grade last year?
I'm by no means a grammarian, but I'd say that the "already go..." version sounds more natural and is probably used more often. But I'm pretty sure your version is used, too. Unless it's clearly grammatically incorrect -- which I don't know -- it seems like a good alternative translation. You might Report it, if you already didn't do so / didn't do so already. :-)