Merrell Tetra Launch Waterproof Boots 6 or 6.5?

I love this style of Merrell boot but sometime in 2015 their size structure changed. In their newer boots I am now a size 7 in Merrell so these boots have no chance of fitting me. I bought these boots on Poshmark and should've returned them when I measured the bottom and it was shorter than my "6.5" boots purchased in 2014. Button missing, as pictured. These look to be in robust condition--soles firmly attached and barely worn down!