The changes to your voice and hair suggest that you have started to go through puberty. When guys hit puberty, a number of things happen in the body, usually starting with growth of the testicles (at least a little). The testicles produce the testosterone, which leads to most of the other changes of puberty. Your health care provider can measure the size of your testicles to see if they are appropriate for your stage of puberty. The penis size typically increases a bit later and doesn’t reach its final size until 4-6 years after puberty begins. Most guys are fully developed between the ages of 18-21. Since everyone develops on their own schedule, your body may be developing a little bit slower. You will likely notice more changes soon. If you continue to have worries about the size of your penis or testicles, it’s a good idea to talk to your health care provider.