How many bridesmaids should I have? help!

Hi all, recently engaged and starting to think through wedding stuff because people keep asking me questions, and I need some thoughts!

Tldr; asking friends to be bridesmaids feels like a snowball situation, but will I regret not doing it?

I have 3 sisters and a brother, and I want them all to be part of my bridal party. I'm also considering having some friends, but have various reasons for not being sure about this:

Lucy is probably my closest friend, she lives close to me and my fiancé and I love her tremendously. If there was one person who isn't my sister who I'd want to be a bridesmaid it would be her. I would love her to know how much she means to the both of us.

Lucy and I used to live with Ellie and Bea, and I'm very close with them as well. We have a close friendship group with them and their partners and have gone on holidays together, have a Christmas do together, etc. So I'd feel like I want them there too, and asking Lucy without the two of them would feel like I'm putting them in a hierarchy.

Then there's Hannah, who we also used to live with. I'm less close with her, but she's very much in the friendship group too. She would definitely be a more 'political' bridesmaid so to speak - she'd be left out being the only woman in the group not asked. I love her and the only reason I wouldn't ask her is we just aren't as close as I am with the others.

Finally I have 2 older friends from uni, Louise and Natalie - neither of them actually are having/had bridesmaids, but both said I would have been one. Louise and I send voice notes every day and also work in the same field so spend a lot of time together; we're also planning our weddings at the same time so chat about it a lot. Natalie and I speak less often but have lots of history, and I'd feel really bad not asking her.

If I ask all of these people to be in my bridal party, that will be 10 people, which seems way too many, but maybe I'm wrong? We're on a smaller budget, so I'm probably going to have to ask them to buy their own dresses (within a colour palette rather than specific styles) and won't be able to offer make up etc. So maybe it's unfair to ask.

Main issue: I don't want to hurt anyone's feelings. Secondary issue: will I be missing out on something by only having my siblings and none of my closest friends there in those special moments on my wedding day?

TIA!!!