Keep learning
If you feel like you have come a long way, you are right. There is always more to learn, however.
Keep reading
You will find that as you make your first app, you suddenly realize that there is a gap in your knowledge that needs to be filled to make some feature come to life. This is normal and guaranteed, so don't let it put you off. Think of how to describe the problem and search for the solution on Google.
You might also find that specific classes in a project will grow beyond the practical and maintainable. This is a sign that there is a better way to structure things and there is probably a ready-made design pattern out there somewhere that will make your life easier.
To pre-empt this almost inevitability, why not study some patterns right away? One great source is Head First: Java Design Patterns, available from all good book stores.
GitHub
GitHub allows you to search and browse code that other people have written and see how they have solved...