Hello and welcome to Healthcare Magic. Thanks for your query.
You have mentioned multiple sexual problems like
premature ejaculation,
erectile dysfunction, low volume of semen, etc. In such a case, it would be best if you have a detailed evaluation from a
sexologist to find out what the main cause of your problems are.
Masturbation is considered as a part of normal human sexual behaviour and is ver common in males of your age group. Masturbation does not cause any ill effects on sexual health and does not lead to any other adverse health consequences. So, you needn't worry about this.
To increase the ejaculation time, you can try practicing certain exercises like Kegel's exercises or techniques like the Masters and Johnson technique. Alternatively, there are medication available which can help delay ejaculation time.
Penis size of 4 inches is within normal limits and so, you don't have to worry about this.
Regarding your problem of low semen volume, it is advisable to have a
semen analysis done to see if your sperm count is normal or not.
Wish you all the best.
Regards,
Dr. Jonas Sundarakumar MBBS., DPM., MRCPsych.(U.K.)
Consultant Psychiatrist