problems

I can't cum or orgasm EVER or at any time. I am 20 now so its really getting frustrating. I have seen 3 expert urologist and have not found anything wrong with me. They did a digital exam, ultrsound of my testicles, cat scan of my abdominal area, urine analysises, and blood tests-all turned out normal. Then i saw two expert sex therapists who in their professional opinion said it wasn't in my head. The way i describe my problem is that i just don't get the good sensations from touching and rubbing etc but i get plenty of erections-so in that sense my penis is kinda of numb. I just went to see a neurologist and had an mri done. The results where normal except for two findings-disc bulge at lumbar4-5 and a central disc herniation at lumbar5-sacral 1. What tests should i look into-my doc mentitioned nerve testing on my private parts. Anyone else have any suggestions? Any referals? All constructive help is appreciated. Make sure it read this through carefully so i don't have to answer any all ready answered questions. And yes i have posted in the men's health forum.

Thanks,
Bob