I'm making a complete plot outline for seven books. It's going linear, meaning it goes from the beginning of the important lore to the end of the storyline. So far I have all the lore down but im stuck three forth's of the way into the first book. P l e a s e h e l p.
Seven books is an awful long time, and a whole lot of content to cover. Have you considered starting smaller and seeing how much you get down, even if it's only 3 or 4 books, and then seeing how you can expand?
You have to keep in mind this series has been in the works for nearly three years now. It was going to be one book, then two, and I kept expanding until I got the double trilogy and intermission book set up it currently has.
As someone who has been working on a series for close to a decade now without fully finishing a book, I can tell you that my main problem is trying to connect everything too early. Similar to what Jynnie was saying about starting small and expanding, If you work on one book with a smaller plot track, then continue to the next and see how they fit, it's much easier to go back and change smaller details within the books.
You've go the lore down, so ask this: by the end of book one, where do I want my protagonist(s)? Where do you want your antagonist(s)? What's the current world state? See what you can flesh out between your start and end. From there, move to book two. Ask the same questions. Are there any outliers that don't fit in place? Are there any spots that can be improved to connect them better?
I had a character that I planned out as a love interest for my MC, I had a pretty fleshed out character for her and everything. Problem was: for how good of a character she was, she didn't fully fit into book one. I had planned too far out of my series and how everyone would fit together that I never narrowed down each person individually. I shrunk my spectrum down and discovered her ownly purpose was to be a LI, but she doesn't add ANYTHING to the plot. I'm sure later I will find a new home for her, but as it stands, she has been removed and I think my plot for Bk 1 has greatly improved because of it.
Now, that's not to say don't plan ahead at all. I do have a villain that I have planned to make an appearance in multiple books with his hand in things, whether he's the main antagonist or not. Ironically by planning the big picture, helped flesh his character out better.
Take this with a grain of salt, though. If it doesn't work for you, no worries, but if it does, I'm happy to help.
Thank you for explaining this clearer. I hope this will help aswell.