I like to use 100% cotton for ring slings. I have one on my Etsy right now that is a microfiber polyester. It's super soft and it works well, but it's not a popular/traditional fabric for ring slings. I have 2 on there now that are 100% cotton gauze so they are super breathable, but that's what I would recommend. I love the name Lorelei! I think Leah and Lily work best with Suzanne, but I think they are all good strong girl names.
I think, considering your circumstances, the bride should make some special considerations for you. I do know that some women are extremely particular about everything being exactly so on their wedding day, but since you are taller and going to be barely PP, it's not going to do her wedding pics any favors if you are towering over everyone with big milk-filled boobs falling out of a strapless dress. She would do better to put you in flats or very small (say 1" max) heels and a halter or strapped dress to contain the boobs. That's my take on it.
Leigh, I hope you get to feeling better quick.

