Let me ask you this-
Are normal classes easy, challenging, or really hard? If normal classes are easy or somewhat easy, then you are supposed to be in advanced classes. Advanced classes are there to be challenging, to actually make you try. And advanced classes in HS will look good to colleges and future employers. That said, if it is so hard you can't even wrap your head around anything even with your parents' and the teachers' help, then you need to talk to your parents and ask them to put you in normal classes.