I have a big uPperbody and a small lower body! Help?

Well I have a big rib cage and big wide shoulders. I'm also big boned. I look so big in my clothes because the bottom of my shirt just dangles around and is loose because it's big... My upper part is good tho. What kind of clothes/brands slim down towards the stomach? What can I do to solve this problem?I'm a 17 year old boy btw. Thanks alot.