Thank you for your query at DoctorSpring.com
Penis size varies from person to person and depends also on the state of erection. A person requires a minimum of 1 1/2 inch of penis to satisfy a woman. Anything beyond this is an add-on and wont help satisfying woman further as its only the outer one third of vagina which is sensitive for sexual stimulation. Rest of the vagina is not sensitive for sexual stimulation.
If your erect penis size is more than 1 1/2 inch then you need not panic. Further the reduced penis size can have multiple reasons and common one are low testosterone or low growth hormone or low thyroid. This can be assessed by doing blood tests for thyroid, testosterone and growth hormone levels. If any abnormality is found, the same needs to be corrected.
Its surgically or medically not possible to increase the penis size. Very sorry if it has disappointed you. But if there is a hormonal issue then it needs correction and the size of the penis will grow.
Hope this helps,
IN case if you have any further doubts, let me know.
Dr. Srikanth Reddy