Hey, Acer, I'm sorry for such long post, but I'm sure that I could relate to your thread here.
I have Penile numbness too. I will explain my numbness in this comment.

I read through most all of the comments you recieved here and I'm sorry that you have been given little sympathy. I haven't seen much sympathy either since I began seeking medical help for mine. I guess it is easy to say that we are seeking attention cause being men we tend to freak out when we are faced with genital problems. But I wouldn't see it as a weakness cause we have to take care of our reproductivity ability (if no men cared humans could end up extinct!), Right? Because of my situation I've taken alot of time and effort searching for techniques, treatments and nutritional advice, so that's how I came across this at neurotalk. That all was promising but for me not the least bit of a cure. Perhaps you'll do well to take nutrition and healthy living as a "must do" since it could avoid some other problem that is potentialy just as undesirable as the numbness or worse. Just common sense is not what I mean to preach, but since you have seen recovery of some sensation, it's hopefull that with time, more improvement will occur. I hope you can keep a record/diary of the changes since that could help others in future if you'd be willing to share it. I've also found info pertaining to injury to a penis from stretching exercises/techniques. I know you're not alone for that type of injury.
The likely cause of my numbness is from nerve damage in the penis itself. I have had Stuttering/Recurring Priapism throughout the past 17 years. This is an erection that persists without reason for times longer than normal (more than 4 hours at a time)causing variable degrees of damage to erectile tissues, nerves, blood vessels, tunica albuginea, and various related muscles. There has not been any reason determined (diagnosis) why I have these priapismic episodes. And in all my research Stuttering Priapism is usually not found to have any underlying cause. In my case it started gradually in my early teens and became most severe in my early 20's then stopped suddenly only to begin gradually again in my 30's. Throughout all this time I've suffered with loss of sensation in my penis to many varying degrees. The worst being in my 20's after an episode that lasted 11hours. It was traumatic to realize that I had no feeling in my penis anywhere like it was no longer a part of me. I couldn't acheive erection or pleasure until more than a year later. But it never ever became 100% sensation since that time. My penis glans has become the least sensitve of all my genital areas. I'm assuming its because that is the longest and most delicate/vulnerable of the nerve pathways in the penis. When I did recover some sensation it was always the frenulum that recovered first. I'm very thankfull to still have that intact since I was circumcised as an infant but have read that some circumcision procedures do remove the frenulum portion too. I seemed to recover sensation gradually but only when the priapismic episodes stopped occuring for longer than a month. And I often had sensation loss immediately after the next episode of priapism. As you might guess my sexlife is an "isn't",but I'm very happily married to the most wounderful woman and have a miracle too (my very own son)!
The other possibility to my numbness is a spinal nerve issue. I have had some traumas in the past to my lower back (car accident x2) (falling on ice ahhh TAILBONE!)(hit in back with baseball bat)(heavy lifting and immediate pain) (riding bicycle BMX style)and (off-road motorcycling). The last two were almost worth the risk but at least "intentional".
I'd be ok with sharing more if you can reach me on this forum or via email. But best of luck and hope your future is brighter.