I'm in a very similar physical condition to OP. I have come to the conclusion that rather than futilely pursuing the ultimate blow job that'll bring me off, I've just accepted that I can't climax from oral. It's been a relief to just relax, let them suck it for a bit and move on to something else. Sorry if that sounds like a cop out of just throwing in the towel ...... I genuinely have a better experience if I'm chilled out and relaxed and not getting worked up or fretting about performing to a certain level.