How to tell my family

This is my fifth pregnancy. Only will be my 3rd living child. I told my mother after a few weeks of knowing because I couldn’t not tell her, only myself, husband, our two other children which are 6 and 2 (as much as she can understand) and then my mother of course. I was planning to tell my side of the family next weekend when we have our Labor Day cookout (my birthday also). However now one of my sisters is having a medically necessary hysterectomy 2 days before the cookout. She has 5 kids and made it clear she didn’t intend on anymore so I don’t think she would be upset but I personally feel it’s insensitive to announce my pregnancy when the choice for her to ever have anymore was taken from her. But I’ll also be 12 weeks already at the cookout and am starting to show. Idk what to do. I want to announce before anyone starts to make guesses. I’m a fairly small person so I already have a decent bump. Mostly bloat but I have a good solid bump close to my pelvic area. Idk what I should do. I want to do it when all my family is together so no one gets left out and the next time that may be is unknown with the craziness of everyone’s schedule now that school is starting back up. Any advice would be appreciated.