Should i ask to be bridesmaid even though we're not best friends anymore?

I'm literally agonising about the decision to ask another friend to be a bridesmaid (I've already chosen my others quite easily). We were best friends when we were at school, she knows my family and we've shared lots of memories. When I got together with my partner we pretty much were out of touch for a few years, I moved to a different city and I'm not sure she totally loved my partner. I rekindled the friendship and since then we're back being good friends. She is someone I can be my self around and I have fun with but we aren't as close as a couple of my other friendships. We don't have a lot of deep chats although we did go on holiday together a few months ago with another friend and I felt really close to her.

In a lot of ways, I would love her to be by my side on the day but there something niggling that is making this a really tough decision which I don't think it should be.
Apologies for the ramble. Has anyone had a similar situation or have any advice?