How happy are you with the results you are receiving? Did you run into any issues?
Your understanding is correct. There is currently no direct way to “inject knowledge” into a gpt model.
Look at the chunks that are retrieved through your approach and identify options for further filtering and/or cutting down the number of chunks to include in the context window. You can for example add metadata for each chunk and then further filter results by metadata fields.
Finally, depending on what your longer-term goals are, you might want to consider storing the embeddings in a vector database, such as Pinecone.
Again, I encourage you to take a look around the Forum and read up on the other extensive discussions around RAG including optimization techniques. Additionally, the OpenAI cookbook also provides more specific RAG-related workbooks including the use of vector databases. I encourage you to explore those as well.
Best of luck with your project! Let us know how it goes.