Talk to Urologist on Precum Problem

I have a precum problem when talking to my Fiancee. Plus when I see erotic videos and stuff. Due to this reason I get cannot get erection with visual stimulus, I have to stimulate myself to get an erection, I mean constant stimulation with hand. When I was younger in teens I never had precum and had an erection almost imedeatley after visual stimulus. PLZ HELP I have to get married in 5 6 months.