So, your story’s not written yet. It’s been years now, and that’s bothering you – Guess what – THAT’S NORMAL!
It takes time to master the writing skill. If you write regularly, you will see your improvement over time, but whether you write regularly or not, improvement will never stop. Growth and development is ongoing and unlimited.
It takes time to get to know your characters. You’re dealing with a lot of people, all of them different from each other. You not only have to discover and portray their personalities but their backgrounds and goals as well. That information will not arrive neatly packaged and at once.
It takes time to get to know your story. As different characters develop and interact, your story evolves. Main areas and scenes might be all worked out, but how they connect and combine adds new flavor and complexity. It takes time for a story to mature and become all it can be.
It takes time to write your book. Deciding or discovering how to express your words, your story, your characters and plot, spending hard time at the keyboard doing it, working it, refining and editing – ALL OF THAT TAKES TIME!
Bloodstone Sci Fi 
Good blog, it’s frustrating when you have a great plot, great characters and all the time in the world can never be enough to fill in the important parts.. The details.
I know exactly what you mean – it took me over 30 years to learn all I needed to (and I’m still learning), to develop and to find my way with my plot for Book One! I don’t like to tell people that for fear they will think every book takes me that long – it doesn’t, I was finding my feet.
It does come. You will get there! Don’t ever give up on your dream! 😀