Hi,
In NAmE, we say 'diaper' instead of 'nappie'..
My son still needs nappies. (It means: He cannot use the potty yet. He still cannot use the potty.) Yes
Does your son still need nappies? OK *** Does your son need nappies yet? /It has probably different meaning, hasn´t it. The second sentence is probably a nonsense, isn´t it? Yes.
- What about: Does your son need a potty yet?/ Does your son already need a potty? We usually say 'use the pottie', not 'need a pottie'.
My son doesn´t need nappies any more. (It means: He can already use the potty.) es. We also say 'he is toilet-trained'.
Best wishes, Clive