I eventually gave up in 2005 in the knowledge that I needed to start again but without knowing why
Similar happened to me, and in my instance it turned out it's because I didn't understand even the basic technicalities of writing. It took a long time to try and understand them, let alone try to put them into practice. Then I had great help from an editor who called out all my mistakes to the point of forcing me to think really hard about everything I was trying to do, and how I was doing it - but even then it took a few run-throughs before anything really began to click.
My suggestion would therefore be to ensure you're up on them - I always recommend reading Wonderbook by Jeff Vandermeer for this, and probably a good idea to watch Brandon Sanderson's lectures as well:
Brandon Sanderson - 318R - YouTube.
You will know some or a lot of this, but not all of it. Simply immerse yourself in everything being written or presented.
Additionally, simply going through it should inspire you to think about familiar parts of your story in new ways - though that's the start of the process, not the end of it.
I'd also recommend reading
Save the Cat by Blake Snyder if you haven't already - I used to think I knew everything about my characters, but reading that book made me realize I didn't even understand the basic motivations that drive them. I've found that book the greatest help in thinking about that depth.
In the meantime, I figure you'll come up with your own insights, images, moments you want to write - in which case, just write them. The really important thing to understand is that you are never going to write a good story in your first draft - you are merely setting out a detailed outline of your story. Most of what you'll do is actually rewriting rather than writing, but you can't rewrite if you don't have the writing there. So forget about being perfect and allow yourself to be as messy as possible - don't even think about editing until you've finished a first draft, as you are going to have to rewrite much of it in the first place.
Don't worry about the rewriting part - it sounds like hard work, and it is hard work. But every time you do it, you make your story smarter, stronger, more concise. That's why you shouldn't even copy/paste stuff from your first draft into scenes - that practice will really hold you back.
Ultimately, it's going to be difficult and a challenge, and you'll need to dedicate a lot of time and patience to it. You'll also need to ensure you have the passion to drive you through the inevitable doldrums and blocks you will encounter.
But make it through all that, and you might just produce the story you really want.
Then get a good editor and go through it all again...
By which time you should be sick to the back teeth of touching it, but struggle through doing so until every change and edit and rewrite you can imagine has all been done.
And that's when you have your story.
Hope that helps, and best of luck with it.
PS: Your experience may be a lot smoother than mine, especially if you use chrons a lot.
PPS: DON'T put anything up for Critique here until you have completed that first draft, otherwise you will end up getting into edit mode with an incomplete piece, and that's liable to freeze you up.