I wouldn't dismiss what you just wrote.

It seems you keep blaming yourself. There is nothing wrong in having doubts. This is (ideally) your whole life we are talking about... So, of course it is important to be sure.

It was striking to me, in your first post, how he has all the cards: HE says you're not ready, HE says you give him cold feet, HE doesn't want to talk about it until you solve YOUR issues. It seems he has a lot of 'power' in this relationship..

How I see it is, IF you have doubts about him then maybe he is not the 'right' one for you.