What is wrong with my bone structure?

I don't know if you have any back pain of any kind for it sounds like you could have pinched muscles in your back and they could make your chest seem to push forward depending upon which muscles are tight. Here is how you can release those muscles to find out if they have anything to do with it or not:

Back:

(do from a sitting position)

Place your left hand on your left leg next to your body. Place your right hand over your left shoulder and find the muscles next to your spine and firmly press on them and hold. After 30 seconds slowly lower your body forward and to the outside of your left leg, keeping your left arm fairly straight as you do. When you reach your lap remain there for another 10 seconds, release the pressure but rest there for another 30 seconds. Then reverse your hand positions and do your right side.

For best results relax your body first by taking a deep breath and exhaling then remain this relaxed.

if you are inclined to put on a little of make-up, you'll be able to create the phantasm of unique bone constitution with spotlight and shadow. it is a little intricate to explain what to do on right here, however virtually, get a basis approximately two or three sun shades darker than your epidermis tone, and placed it at the locations you wish to slash. additionally get a lighter basis and placed it at the locations you wish to stay out extra. most likely, mixture a ton, you do not wish it to appear visible!

I don't know but you should go see a doctor and ask about it. That seems very strange to me.