Hello, Thanks for using healthcaremagic. Your concern is normal as it is the concern for many of men like you in today s world. The question arise is why you want to make your penis size big?! Most of the men think that bigger the size, more the excitement and more the satisfaction to the female partner.But practically for orgasm size doesn t matter at all, as only 3 (inch) of vagina is sensitive for sexual arousal.In erect position 4.5 you mentioned, which is quite sufficient so you need not worry for current size. As a human being we have many variation in many parameters like height,weight,daily food intake, work capacity,intelligence level,stress tolerance capacity,immunity and so on but we are living our life individually according to our parameters.Like these penis size varies according to race and body structure, there is no specific criteria that this much size is good.So according to your body structure it is normal. Practically there is no treatment for increase penis size as it is not problem in your case. However I would like to suggest few things.You can have multivitamin which contain methylfolate; avoid alcohol,smoking,tobacco;regular exercise and use cow milk ,cow butter,garlic in your food.These might help you overall to increase blood flow in your penis and so in size. Hope I have answered your query, late me know if still any info needed. Regards, Dr. C. K. Solanki