Keeping Comms Active

Is anyone else getting discouraged? I lead or co-lead four comms. (Two of each.) One of them is a Power Rangers community- lots of new material, easy to post frequently- I barely get comments. (There are only six people.) In the Young Wizards community other people have made posts! But because it's a small community (almost 40) and we have awhile before new material comes out, it's hard to keep active. In the other two, I've been doing group rewatches. I was expecting a small response in the Tomorrow People community, there's only 10 of us. But the Dark Matter community is almost 150 members, and three of us post. So far, other than a couple likes, the group rewatches are getting no additional traffic. Anyone have suggestions?