As funny as this may sound, have you tried the juniors section for shorts and t-shirts? After being given several youth large t-shirts from middle schools I visited, I realized that they actually fit me just fine (5'11" 150 lb btw). I'm also quite sure you could find some shorts at JC Penny or Old Navy meant for teens. As for jeans, I know they make 28s but it's hard to find jeans with an inseam longer than the waist here in overweight America. In that case, you can order the jeans from JC Penny catalog and try them on in the store before you take them home.