Hi,
The size of penis when erect can can vary from 10-14 cm so that suggests that you have a normal length of penis.
Veins under the skin are normal,unless you have any symptoms like ulceration,itching or any disfigurement over your penis.
The age is fine when you started masturbating most people start it around the same age and continue with it till they are married and many people do it even after marriage to. ...
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