Can anyone recommend a retailer whose trousers and joggers are on the slim side, without using adjustable waists? My 6 year old son is very small around the waist but with long legs. I can't buy younger sizes as they would be half-mast! Trousers rarely fit him unless they have an adjustable waist but he's starting to complain that the bunching up is uncomfortable. Also he could do with some jogger bottoms but they literally just fall down his legs! Any pointers would be helpful...