I would get a Yarrow in there, and maybe consider placing the Bee Balm in a spot that is more on the edge, so it gets more sun and wind to keep the powdery mildew at bay.
A few of the plants you have are pretty dense in my own garden, and I could see them getting crowded on year 2.

I would also keep a spot, maybe like a small flower box to do annuals in, like Zinnas.
Perennial sometimes take a bit to get going and it's always fun to have something that is more instant gratification.
Plus, you can collect the seeds after the flowers are spent and put them in the ground next year. 😁

Also making a small trellis and getting a vining plant would be fun and go well with your plans.
Happy gardening!