This is so difficult shy, I completely sympathise. But reading the book might give you pointers as to what to say/how to say it.
It took me years and years to understand that I needed to be at a certain level of arousal to enjoy sex, so I think you're doing well to know your own needs...a lot of the time I still don't get it right, and it's annoying to be pounding away thinking this could be better! sorry TMI
I wish I had a solution and hope the book helps. It sounds like you are doing everything right and maybe one day he will have a breakthrough.
The only things I have ever found to say at the crucial moment sound like cheesy dialogue from a bad film, but that's sex for you - 'What's the hurry darling' 'Hold your horses big boy' Yuck! but it makes me laugh which helps.