I was feeling the same way and thinking I should make more videos and felt stressed out about what new videos to make. I've just kind of laid low for several days working on other video stuff. I didn't promote (so no new subs for several days), but I kind of needed a mini break. I might not post a video this week. YouTube is a marathon not a sprint.New I had considered trying to post daily to try and make more progress but having to also work on channel art myself etc, I know I would get stressed out.
So now I've decided to just continue as I have so far and hope it gets better ^^
There is nothing you can really do. It just happens. I tend to ignore the numbers for the most part. It is not fun seeing them slow or fall. That is why I focus most of my energy on creating the best content I can create and loving (for the most part) the entire process, from filming to editing to posting the final product.