I've been listening to the Chris Loves Julia podcast and it has encouraged me in many ways, but the top 2: 1. Don't be afraid to scrap what you've done and start over if it doesn't feel right. and 2. Sometimes the cheapest "change" you need, is simply to rearrange the furniture. So here's how I fixed it.

1. Take it all out!
First, I perused my kid rooms Pinterest board to see how other shared rooms were set up. 9 times out of 10, the twin beds were close together separated by a simple nightstand. So I eliminated the vanity, which they never used as I'd imagined anyway; it simply became a landing place for stuff. I also got rid of their nightstands. I removed almost everything in the space to figure out what it really needs.

2. Research (use others' expertise)!
As for all the color, I searched "pink buffalo check" on Pinterest to get ideas for what people paired it with. The headboards were a super time consuming DIY and belonged to Joe's dad and uncle when they were kiddos, so while I might swap them out eventually, I'm not ready emotionally or financially to do it now. Laugh face emoji at how serious I'm making this sound. But you get it! I'd pinned Chris and Julia's daughters' room and LOVED the pattern play.
I also loved Emily's daughter's duvet paired with black and white dots, via Jones Design Company.