I'd say they fit similarly to the Okalas, but are a very different shape. I have narrow heels and a wider (normal?) front part of my foot, and they're relatively flat and low volume. I wear a 9 in both the Okalas and the Trinas.
The ankle strap is adjustable on the Trinas, and the front strap is more forward than the toe part of the Okalas, so unless you have very high volume toes specifically, that could be the adjustment you need. On me, the front strap runs from my pinkie toe to just in front of that outer joint by my big toe (so not the widest part of my feet). I'll also say that my toes are just shy of the front edge of the shoe, so I contemplated sizing up for length, but decided against it. Going up a half size may give you some more volume in the shoe without causing length issues.
Amazon has free shipping and free returns on shoes, so I say go for it
