I have an answer that I've given to a lot of people and none of them have seemed to like it. So before I give it to you, I get that at core, you want more readers.
The answer is that the people who subscribe here are subscribed to a lot of publications, topics and authors. Typically it's way more than they are willing to read in a day.
So when we put together a feed for them we are able to often create 1k viable candidates which we then have to whittle down to 10-15.
Basically that boils down to many of your followers have been choosing other authors more than you. Maybe tough to hear, but we don't think it's entirely unfair.