Update:

So I sucked it up and went to the shower of course, was still pretty anxious at first but ended up having a good time! Everyone kind of made it more about welcoming me to the family and got some really nice gifts for our baby girl and personalized notes from different family members as well as a Thanksgiving invite. Thank you for everyones input, definitely brought up some points I hadn't considered

So I'm 33 weeks today and already had a small early baby shower with my friends/family a few weeks ago. I've already bought pretty much everything I need so it was really just to spend time with people I haven't seen throughout my pregnancy. Then like a day after my shower, my SO tells me his sister is throwing me a baby shower(today) with all his family. (Just to add, I did try to invite his mom, sister, etc to the first shower and I never got an answer nor did they show up). So his family are great people and I really appreciate the gesture, but I really just don't know them very well and I've tried several times to nicely express to my SO that I don't feel comfortable with it and I don't want to be essentially the center of attention for a bunch of people I don't know. He's pretty much just told me I'll be fine and that he'll be there with me. Then last night he cancelled our dinner plans to help set up, and pretty much just partied with his family all night. Now I honestly feel like me going today is even more pointless since they've already had their celebration. Am I being too dramatic about all this?