Suggest Medication For Penis Erection Problems

doctor im 30 years old i have girl friend since 8 years and we had good sex life now my problem my penis not getting hard by viagra to it work after 2 or 3 hours but problem is that im drinking alchole and in the middle of an hour im having viagra but now is problem my penis is not getting hard sometime it get hard but after few minutes is become small please help me out im having omega fish 3 and androgen (tribulus terrestris extract compound ) it that better for me ? help me out plz