This study examines the integration of Project-Oriented and Problem-Based Learning (POPBL) with Generative AI (GAI) as a teaching assistant (POPBL-GAI Education) in an eight-week chatbot development micro-course on maternal health. Leveraging ChatGPT, students engaged in self-directed inquiry and problem-solving to develop a chatbot addressing maternal nutrition, symptom management, and dietary needs. The findings suggest that this approach enhances self-efficacy, fosters learning optimism, and reduces cognitive load, indicating that GAI-supported POPBL can effectively promote student engagement and learning confidence. Notably, frustration positively correlated with learning optimism, implying that appropriate challenges may deepen engagement. These results highlight the potential of AI-assisted, inquiry-driven learning environments and their broader educational implications.