How big does white mistflower get? / Spacing

Ok I read a lot of conflicting info. Many sources say white mistflower gets up to 6’ tall while others say while true, 2’ tall and wide is most typical. I’ve planted a bunch in my full sun front yard. They are almost a year old and look to be around 2-3’ tall/wide right now. My question is… should I expect this to be it? Or will to get bigger? I spaced them too far apart if this is it so will add density if the consensus is that in Austin full sun they stay smaller. Please let me know!