I'm going to my bf's brother's fiancée's bridal shower

A
So.... my boyfriend is 17. I just turned 16. We've been dating for almost 6 months. His brother is getting married soon and I am invited to the bridal shower. I am nervous because I'll be meeting all his female relatives in one room when we have been dating for 5 months. I don't know if it's a good idea for me to go especially, since he won't be there. I don't want to have it be awkward and I also want to make a good impression. Help me. Is this a bad idea? Should I go? I don't think they're going to be people my age at this thing. I don't know if my boyfriend and I are going to stay together forever. I mean I love him. But we are teenagers. Do I bring a gift if I go? What do I wear at this bridal shower? Since I'm not going to the wedding is a good idea for me to go at all? Do you think he's going to do something crazy like propose anytime too soon now that I'm invited to these kinds of things? I don't want to get married right now. Heeeeeeeeeeeeeeeeeeeeeeeeeeelp.