So I'm deciding if I should stop doing let's plays of custom stories and...

[Slanderous]

Don't do let's plays, there's a ton of other let's players on the internet so why would anyone watch your particular series? Try to come up with something fresh, new and original that will attract people to your channel. Sure, it's a very difficult thing to do, but no one said that the path of becoming a YouTuber is easy. You gotta work hard, learn new things, study the tricks YouTubers use (tags, appropiate thumbnails, catchy names) and in my opinion you as well need a lot of patience, one of the most lacked traits that people struggle with.

I'd say start with asking yourself "Why would people watch my channel?", and then try to come up with an answer to the question.

Good luck on that!