Upset Bridesmaid- Sorry its long

So im getting married next September. My 16 yr old sister is my MOH and my bridesmaids are my bestfriend of 10 yrs and 3 cousins (2 of them are sisters on my fathers side and the other is on my mothers)

I dont want my shower to be a surprise so Ive been pretty involved the whole time but not in their fb conversations about it. My mother is contributing most of the funds for the shower because we are paying for the wedding ourselves, the bridesmaids will contribute about 250 each and she will cover the rest. My mom really wanted us to check out this restaurant so we made a reservation last week for brunch today, just us girls and my grandmother. The two sisters told us they weren't coming. I have no idea why one didnt but I'm pretty sure the other didnt come because she wanted to bring her boyfriend and my mom and sis told her no it was just for the girls and we wanted to keep it that way.... it was to try the food and meet with the planner at the restaurant. I loved it so much my bestfriend put a 200 dollar refundable deposit down just to save a date in July- not set in stone.

My sister sent a message to the two cousins letting them know and also reminding them that they have brunch every sunday if they wanted to go and see how they felt about it.

I get a message 30 minutes later from the cuz that couldnt bring her bf and she said shed have appreciated it if she was included in the decision... are we wrong? I feel bad and idk what to do. She knew we were very interested in this place and she even emailed and spoke to the lady at the restaurant herself last week. Idk what to do I feel like I did something wrong.