I think (forgive me) that you too intelligent for your own good. You're trying to fix this, because you're clever, you care, are driven, well informed and well read on relationship matters.
BIG GUNS.
I think he needs professional counselling - and even really Relate, though that might work in tandem. I think there are deep issues here. And you can't fix them.
On specifics, you did amazingly well to get him to mention his cock to a GP! But there is a limit to what you can do - he has to say "that's not enough doc" and he has to want to sort it. The sex, but the relationship too.
I think you'll wear yourself out trying to fix it, and you'll be too weary to go on.
I have no psychosexual evidence for this suggestion... But I wonder if he could go to therapist to work on his own anger (e.g. about the SAHM issue)
Btw - he may massively resent that income. He's out working, and he can't even pull the "breadwinner" line on you. He shouldn't anyway, but he may feel disempowered by it, and resentful. I'm digressing...
So, intensive individual for him.
Potentially psychosexual too, but depends on whether his individual leads you to conclusion that he has an issue affecting your sex life, rather than a sex issue.
After a while, marital for the pair of you.
In the mean time: a pact - you tell him you won't talk about sex for x period. But he mustn't wank over same period. Hard to enforce, but he may as a side issue be training himself on too specific fantasies / porn / death grip. Perhaps it would help if he too were, ahem, gagging for it.
Take a psychosexual counsellor' advice over mine on that though!
It is AWFUL not having sex. Not just the physical lack, but it fucks you over emotionally too.
Next thing you know, you're in a wine seriously considering shagging a wanker with a yacht photo who is only stroking your neck cos your mate told him to fuck off, and cos your other mate - top dog - he's too scared of.
And yes - you know me xxx
I'm only breaking cover because I'm sure it won't bother you.