Hi Mandiz, What you need to do is take an 8 week sabbatical, you need to do this to reboot your body, so its no masturbating, or any sexual contact for all of the 8 weeks, and if you have been doing it to porn, clear away all your sites any downloads you have, and get rid of any discs you have.
Its the only way forward for you, after the 8 weeks come back and I will give you some tips on giving your p***s some more life.
Good Luck
Hi and welcome. Its not getting smaller, your getting less stimulated with the masturbation, hence less blood for erection.. I would cut down doing it for a while