DS has just turned 3, all his 2-3 clothes are too short but still pulled in a fair bit on the waist, I have tried age 4 (john Lewis) and the length is ok (turned up a bit) but the waist is huge. Where can I get decent quality jeans/trousers that are slim round the waist and ideally have popper opening not buttons that don't cost the earth as they will be trashed at nursery.