I don't think it should matter all that much if your stuff gets pirated. The reality is that if they're pirating your book, they probably wouldn't have paid for it anyway. I feel like most people I know pirate books to get a feel for the book before they go ahead and purchase it. Almost like an extended sample. All my friends who end up liking their pirated books typically spend the money (given they have money) buying actual copies afterwards.

The real number that would help you is finding out how many unique user downloads there were of your book and asking yourself if your marketing was strong enough to get that number of sales naturally? Or worse, is it that no one is downloading your book even with it being free?

I am biased since I write free content and believe in getting sponsored by supporters, but being the distributor of my free content and able to view download statistics, I can see that marketing is my biggest problem and no one wants to consume even my free content