Welcome to the forum I live in portugal only it's not in portugal and its called the netherlands so I guess im close. All kidding aside just relax and don't overthink it. After all it is important what your boyfriend thinks of you and not the friends. He would not show you to them if you were a complete idiot trust me i know
I'm portuguese as well and just found this forum, like you.
I think that you boyfriend will help you with that, feeling comfortable around his friends. If not just let him know how you feel and maybe he will understand that he needs to help you get some confidence around them.