Quit being obsessed with height
You'll look fine on a smaller horse. I'm 5'9" and use to work cattle with a QH about 15 hands.
I personally would be happy if my 16.1 mare was an inch or two shorter and I'm hoping that my youngers mare will stop now that she's about 16.3 (shorter would be better).
She's already tall enough that I have to find a depression, stump or something else so that I can remount when out riding. Also means I have to pull myself a greater distance up which pulls the saddle against the side more when I mount (not comfortable for the horse).