I believe Bjorn is older than you.
Anyway, theoretically it shouldn't matter. Your chest structure is controlled by your muscles and tendons, not the bones itself. The bones and the attached cartilage is pliable. It has to be for you to be able to breathe properly.
It might take a bit longer when you're older, because you have less collagen in your bones than a teenager, but it's not like you're 70 years old. You're 31, which is still pretty young.