Hi sir,
welcome to health care magic,
I can certainly understand your concern and worry about your sexual performance that because of your over
masturbation ,skin over penis gets over keratinized and sensitivity will be decreased as you mentioned that you used to masturbate for 4 to 5 times since 12 yrs, this could be over masturbation, but nothing to worry I can suggest you some techniques to increase the sensitivity with drugs like
sildenafil which increase the production of nitric oxide ie NO, which stimulates your erections to last longer.
So this problem is definitely reversible you can get long lasting erections with above mentioned drugs , in addition avoid smoking and alcohol , and perform some
pelvic floor exercisesas you are still young .if you are doubtful about semen, you can undergo
Semen analysis so that you will be confident and stress free about your marriage. Porn addiction may also increase your threshold for sexual stimulation, so try to avoid that.please consult your
psychiatrist for further help
Please send your queries if any, I will be available to answer them
Thank you.