i m suffering from weak erection,pls can someone help me.

i m suffering from erectile dysfunction,and this is affecting my relationship badly,not that i dont wakeup at all but when i wakeup it wont be long i will be feelin weakness in that part and most times my erection is not strong enough for penetration,no matter how hard i try.have consulted some medical practitioners but most of them says is psycological but i dont believe because i know my state of mind at that moment.pls is there any tin i can do to cure myself from this problem.pls your opinion or sugestion will be highly consider.