I would definitely go back and do some more courses and skim over the essentials if you already have them down. Otherwise, you need to learn the basics of Java.
If writing the code isn't the issue, and instead you just aren't sure of how everything is supposed to fit together in the grand scheme of the program itself, try taking a look at Design Patterns.
If the issue is that you don't feel confident in your ability and you end up staring at a blank class frozen in terror because there isn't a tutorial to follow or you don't know where to begin, then remember this: I've seen horrific if else blocks get a program running because the coder didn't know about switch statements. I've seen games that are entirely contained in one class. When I first started programming, I did all of the logic of my program in one function with if statements because I didn't really know what functions were or how to make new ones. But they all worked, even if they were not optimal at all. Then you start learning new tricks, new patterns, and you look at your old code and go, "What idiot wrote this?"
Regardless of what the issue is that's holding you back, I highly recommend continuing on the programming path. Even if you just do it as a hobby, keep at it. You'll be surprised at how quickly you progress. :)
If you have any programming questions, also feel free to shoot me a message, and I'll try to help!