I have the same problem as you. But after a lot of trying to figure out what is going on, it seems that my level of sensitivity is not that great. If your level of sensitivity is high, as an extreme, you could have premature ejaculation. Mine, and maybe yours is low. When I use a condom, I don't feel hardly anything, and I lose the erection. Without a condom is much better but I still can't cllmax and I will lost my erection at some point after awhile because I still don't feel that much.
I was extremely horny at 20, (now a bit less at 40) and when I lose my erection, I still am horny, just no erection. I then do other things, until my erection comes back. And, the process repeats all night.
I still say there is some physical problem blocking my sensitivity so that it is not normal. Maybe a supplement or nutrition will fix it, or some type of cleanse. I just don't have an answer yet. Certain supplements will help with the erection, but, it's like I can stay harder longer, but I still can't feel much or cllmax.
For awhile I thought maybe I was injured during circumcision, butI don't believe that to be the case. It's some nerve damage or nerve blockage I believe.