Indie books appear on the market every single day. The only way for self-published authors to keep up is to keep publishing more and more books, right? It's nice in theory, but it's not all that practical for authors who maintain full-time schedules and want to write really high-quality books. It's okay. You can just write other stuff, too.
The Next Best Thing
Can't write four new novels and get them published this year? You're only human, so don't be discouraged if you're not writing and publishing your books as fast as you'd hoped. However, it is important for you to stay in the game and keep your name out there. There's only one thing you can do: write other stuff.