Switching Gears Is Hard Sometimes

I'm between projects right now. I have been for six weeks and if you want to know how long I've been floundering, you'd be completely correct to guess six weeks.I usually flounder for a little bit but this floundering feels a little bit long because the project that ended, Second Position, hasn't really ended. I'm doing promotional work for its April 13th release. So I keep going back to that world, keep reading the book for teaser quotes, keep thinking about the best ways to get people to pick it up and read it. This is the first time I've really faced this, obviously, where you're promoting one book, heading into edits on its sequel, and writing a new book in a new category.I know what I want to be working on--a book I'm calling Sad WIP or Sad Book on Twitter because it's so sad, you guys--but that book's one of those slow books, where I write 300-500 words at a single time and hope that it's making progress. The biggest problem with the book right now is that I'm at 20,000 words (a typical area for me to struggle with a book, interestingly enough) and it's so sad that I'm not sure that I can finish writing it, much less get anyone to read it. I know that in revisions, I'll probably move things around, cut things, and move my Symbol of Hope up earlier in the story.  I know that I can insert more hope in the story. I know that even when I write terribly sad sections of books, one of my strengths as a writer is to hold onto that thread of hope.Maybe I'm holding onto it without seeing it right now.I hope I am.I'm also doing preliminary research on the next books (my first YA duology or series? Normally I write YA standalones but I'm really feeling the duology with that project) and hoping that something grips me. And soon. I'm simultaneously telling myself that I need to take the pressure off the book, and myself, that it's okay not to write a book in a month--it can't happen every time anyways--and reading 2K To 10K: Writing Faster, Writing Better, and Writing More of What You Love (amazon link). And by reading, I mean, I bought it, and it downloaded, and when I have free time, I'll read it?I should probably stop lamenting how I can't write and just go do that ;)tl;dr Writing is hard