Brand new fleece sweatpants 2 pair

I ordered a size 10 when purchased, I got them and they are way too big to be a 10!I would think they would fit a 12/14 or 14/16 big boy. they have soft fleece inside! one pair that is dark grey with two white lines down both sides and the pair that are black with tan lines down the sides. absolutely perfect for winter!!!!! They have never been worn or used! they are in perfect condition!