Hello dear,
The size of penis is genetically determined and it does not increase after a certain limit.
But one thing should be known that the size of penis does not determine the potency of an individual.
It's only the outer 2 inches of vagina that is sensitive, which means that a penis of 2.5 inch and that of 6 inch will cause same amount of sensation and pleasure irrespective of their sizes.
Semen volume as well as sperm production can be enhanced with the help of Nutritional supplements &
vitamins like Vit E, Vit C, Vit B complex,
Folic acid,
Selenium, Zinc, L-Carnitine, etc.
One more thing, kindly do not get influenced by any
over the counter medication which claim to increase the size of penis or improve performance...it may be harmful.
Wishing you a Good Health.
Take care.