Ref author book sales, the average per title sales in the USA for 1.2 million book titles released/year is roughly 200 copies, so you're not alone. However, I recently read an artcile which cited about a dozen SP authors that are clocking sells big time. Not sure what their strategy is, yet I have read where several authors have had good luck offering their books free for a couple weeks then switching to charging and it appears to drag across followers that now want your back list. Amazon uses their KDP program for this, bad news is that you have to commit exclusively to them while in that program.