Clarinet players: How long did it take you to play high notes decently?

I'm having a lot of trouble with them. I learned them I think in fifth
grade and my teacher didn't really bother to go over them that often
so now im going into eighth grade trying to play the music for
marching band and it's so frustrating. Is this normal or should an
eighth grader be able to play high notes??
Ughh. :/