Great job on making it as far as you are. It means something is working. As for how to best prep for Wednesday's interview, I would recommend you record yourself answering the question, "Tell me about your experience so far." And play it back to yourself. It will sound AWFUL at first. But do it like 10 times and you can start to iron out your story.
Big things to focus on when talking about your experience:
- what you did, how you did it, and the result
- spend time on your most impactful projects.