Hi Trish. You certainly have my sympathy -- for years I felt this way about my sister. Loved her dearly, and we were super close; could almost read each others' minds and that sort of thing. But she was much as you've described your sister: Loud, brash, rushing in where angels feared to tread, and imo attracted all the wrong kinds of attention to herself. She had a form of social immaturity and Aspergers, which could make her tough to be around -- and she was famous for her temper and going off half-cocked on half the information she really needed to make a mature decision. She was also huge amounts of fun, smart as a whip, impulsively generous (sometimes to her own HUGE detriment) , smart-mouthed and hilarious.
Sometimes I found her exhausting. She could weary me and wear me out. And I have been mortified in the past when she would pop up in the midst of people I knew well, and so/say/shout something inappropriate or just too loud. Finally decided that I'd be cautious with my friends -- She was family after all; I just laughed and rolled my eyes and said, "Yeah that's my sister Laenie. She's Four-foot-nine of intense." Shrugged and went on about my business/fun/whatever. Some people got used to her, some never did; Oh well?

I miss her. She's been gone for many years, and I still wake up thinking, "I gotta call Laenie and tell her...." That's not an option for me anymore.

Whatever you decide, your sister's personality is probably pretty well formed and set by this age. Doesn't mean she can't and won't learn and grow and change -- we all do. But she is who she is, and you'll need to decide how much of that you want in your life.

Best,

Chyia