Your workmanship is very good, tillering, well, sinew may keep it together in spite of the hinges.
Take a good look at your limbs, not much bending from the handle to mid limb on both limbs then lots and lots of bending.
I will send you a tillering gizmo if you want one. It will help you get the whole limb bending without hinges.
By the way, my first bow was a sinew backed osage bow made from an osage board. My tillering was so bad the bow blew after about 30 shots. Not even sinew could protect it from my sorry workmanship.
Another thing I do is wait on backing a bow with skins until I have it completely done, shot in(about 1000 shots) and am sure it will hold together.