For those of you who have ordered from jiffy shirts, could you help me with a sizing question? My 7 year old normally wears a size 7 and my 4 year old wears 4/5. I'm not sure what size to get for the 4yo. The measurements for the XS seem like it would fit him, but the size 2-4 confuses me. I'm worried it will be too small. Anyone have a child this size you have ordered shirts for? Do these shirts shrink like the ones from Wal-Mart?