I want to write a book, but I don’t know which book!

So, today I fired up my laptop, determined to write something. But my head is all confused. My problem is not that I don’t know what to write but that I have too many things to write. Swimming in my head right now are ideas for:

Two memoirs
A romance novella or two
A sci-fi epic
Several short stories

And sitting in my hard disc are:

Several half completed sci-fi stories
Some completed stories that need to be edited and put up, well, somewhere

And at the same time I have to:

Write the last two books of my Trixie Koala children’s stories
Write several columns for Reading Revolution
Get cracking on the Young Adult novels that I have for Discern Publishing.
Write copy for my day job at the Social Media agency.

OMG, no wonder I’m confused. I’m all over the place! LOL. I have way too much to do and to process and my head is running all over the place trying to figure out what to start first. As usual, I’m overcommitted. This has always been a problem for me, and something I need to learn to have a handle on.