is "gdzie" just translated as "where to" or is it also simply "where"?

Shouldn't it be "dokąd idziesz"?

Dokąd is more formal than gdzie?

My Polish teacher says "dokąd idziesz" is proper form. You could lose points in an official test for "gdzie idziesz". Polish natives say so, but they don't have to pass language tests for permanent stay permit or citizenship.