OP, I think it is a bad idea to equate his decision not to have more children as a reflection on you.
I think a lot of men are very cut and dry regarding having children.
They know how many works for them, they don't have the hormonal surges women have, so they are capable of making a very clear unemotional decision.
After our last child, after months of no sleep, and us both being on our knees, literally, it was hell.
Suddenly she started sleeping all night..
It was amazing...a whole new world.
I got into bed and started to say "do you know what?"....and he, quick as lightening said "Nope, not happening, I'm done"....I burst out laughing, said no more, ....we never discussed it further.
I knew he was done, I also knew that my hormones were still raging in my early 40's even though I was also done.
I think some counselling is a great idea to tease out what you want.
But accept his decision and start focusing on what you really want.