USE AROGYAM PURE HERBS KIT FOR SEXUAL WEAKNESS you can easily increase your sexual stamina without any side-effect
Did you get your testostarone levels checked? Just because the DR says it is normal don't trust him. Your levels should be at 900 at that age. Not 200-250 which still falls in the normal range according to the text book. Are you tired alot? depressed? anxiety? sparce facial hair growth? All signs of low testostarone.
Can you do PC's or kedguls, you could try jelqing, I've read this may just help you, Google PE or p***s enlargement, and look for pegym they have a starter page, work from there, saves going on drugs and its more natual.
Good luck