What can i wear to a babyshower at a banquethall?

Hi, I was invited to a babyshower this saturday at a banquethall and i was woundering what would be the proper attire for me. The invitation never specified what i should wear, since it is at a banquet hall i would ume jeans are not the best option so i would p on wearing jeans. I thought about wearing a gray and black leopard printed romper which is short and strapless with red bootlike heels. Also, iam not very familiar with the people from the party theyre related to my boyfriends parents and also i ume a lot of young people would be going because the parents are just 19 what can i possibly wear? I am 15 5'3" and 100 lb. I would like to mention too, that i would be staying over my dad's since tommorrow till a bit after the day of the babyshower so i would be carrying bags of clothes with me do i dont want something that would occupy much space :) thanks