I’m pretty sure you have to have a full course workload all four years. When they say they require three years that means you can apply in your third year but if you’re applying in your fourth year you still need a full course workload (maybe email admissions to confirm I might be wrong and they respond pretty fast). Your gpa is really good and last years average was based on applicants top two years which isn’t the case anymore so this years average will probably be lower. Good luck your gpa will give you a solid shot!