I need some help with my stories

Hi, this post is mostly to other writers who follow me or might happen to read this. I have a big problem with my stories and writing.

The main problem with my stories is not that I'm out of ideas (got enough ideas to finish my fanfic "Rainbow in the sky and a sequel) but to actually continue writing. I always see other writers and how fast they publish new chapters or stories while I just can't start to work on a new chapter although I have plan about the many details and the main plot of the chapters. I exactly know where my story is going, what the characters are going to do, what they will say and how they evolve during the whole story.
I don't have any problems that might cause the writer’s block I have. I finished my job training with a good result and got a job, I don't have any life or money problems or anything else but I just can't start to work on my stories

I hope someone might be able to help me