Premature Ejaculation

Patient: Hello Sir,I am a single man age 24I have problem with my penis erection and size.My penis grows hardly to 3 inches when erect completely, and loses erection in less than 4 minutesAs far as I know my biggest mistake was that I masturbated a lot in teenage but now i have reduced it.Is there any possibility that my penis can get a better size and increased erection so that I can lead a good sexual life with my Partener.Please suggest a natural way if possible.Thanks