Find a known Urologist or specialist in ED. There are various tests to determine your issue and your suitability for various remedies. Most GP's have little training in ED but they can monitor your prescriptions once a specialist establishes a proper treatment. You might be surprised how quickly this can be resolved by a trained and open minded ED doctor who can customize a treatment for you.
Think of your woody like a room with a ceiling and a floor. Too close to the floor and you lose your erection. Too close to the ceiling and you bust too soon. An ED med can increase the space between the ceiling and the floor - increasing your confidence and lessening anxiety. Viagra, Cialis, Levitra, and / or Spaedra / Stendra can be fine-tuned for you by a competent specialist. Some people just go to a GP and may get lucky and find a GP who is open to trying different things to see what works on an ad hoc basis.
Or you can waste more time trying Bolivian Tree Bark, Emulsified Monkey Balls Lotion, or just thinking about Madeline Albright if you get too close. Or you might just try some Levitra under a willing doctor's supervision. Other people have lived before you. Put Premature Buntulation in your past and swing the bat like The Bambino.