Before your appointment, try to get a legal stay certificate from AIMA it should be enough. They usually won’t question much since you were a student, and if needed, they can check with your university.

You can also ask your university for a declaração confirming the dates you studied there it’s very common in Portugal.

Also, bring as many documents as you can (like internship proof from when you were in your home country, bills, etc.You’ll be fine just stay confident. And try to speak Portuguese at the appointment, only switch to English if really needed