Birthing partners?!

Khloie 🇬🇧 • Baby boy 10th Dec ‘17 🐒 Baby girl Aug ‘19 🤱🏼
I'm 21 and having my first baby the end of November. 
I have a twin sister and a mum which I'm not really that close to and she's not a positive energy to be around a lot. I'm close with my sister but she's so much in my business she thinks she's the one whose pregnant. 
Originally I've always said when I give birth it would just be me and my partner, eventually caved in and said my sister can come in with us. 
HOWEVER. I now really don't want her there. She's never had kids so she has no previous experience and quite frankly I don't like how she doesn't support me at the present moment. She tells me how tired she is of hearing how sick I am etc and has even had a few digs about my weight. 😑
Mum mentioned today she should come in with me, but in a million years I would never want her there. It's not happening. I really can't see me changing my mind on that. 
Has anyone had experiences of just being with their partner while they were birthing? Especially when you're both first time parents. If anyone's got any advice or encouragement I would greatly appreciate it. Thanks 😊😊