How do I know if I'm programming procedurally in object orientation?

It's hard to say what's right or wrong, because everything depends on a context, but in object orientation there are some topics. Some things that can help are:

• Avoiding giant classes (also known as god class).
• Separate the parts of the software into components with a well-defined responsibility.
• Create objects to represent the parts that make up a project.
• Use composition to make objects work together (Injection dependency is a great practice to do this).
• Study SOLID principles.

Anyway, there are several topics, I mentioned some that I think is important. Begin by trying to understand the principles and be critical of your own code. Object orientation is a complex subject and very conceptual, one must always be studying.

When you call a procedure directly without sending a message to a specific object so that it takes care of it you are being procedural.

When you tap properties of an object outside the object's own class you are being procedural.