I am 23yr male. m very much concerned about my penis size and girth. 13cm (around 6inch) is the length after  getting fully erect . I want to add few more centimeter like around 16cm(around 8 inches) and also want more girth. help plz.. I want some natural treatment , if possible. i realy want to grow  more girth its important and size also...
Gentle massage with bala taila elps to some extent. But beware of false advertisements. Size can increase only to an extent. For considerable change surgery may be needed.  But as a general advise the size of penis has negligible role on sexual activity/performance.