I just completed all the JavaScript challenges and lessons, I still don't feel comfortable with it. What should I do now?

Start thinking about something, anything, and write in pseudocode and start writing the pseudocode into code from top down. then place it in gitHub and/or your website.

Summary, Do the bold things listed above.

If your not going through a guide within FCC as of yet, I’m heavily in here at the moment (I’m a fellow newbie (with a few years under my belt of going through the “lessons”)):

https://forum.freecodecamp.com/t/computer-guide-computer-science-and-web-development-comprehensive-path/64470

Within, there’s a great course directed towards what you may need to go through. The course is “Effective Thinking Through Mathematics”. It has helped me to think more and write the program given (from scratch). Now I’m thinking like I’m in the Matrix sometimes as I’m outside and not interrupted for a moment(s).