Get another piece of wood and have another go.
I'm working on that, since I live in the city I kinda have to rely on ebay/ lumber stores, and the lumber stores I've checked out have mainly pine, oak, and cedar, so I've been mainly on ebay keeping my eyes on some staves there
that thickness taper looks all whacky.
the lower limb looked pretty weird but I had it bending pretty evenly along the whole length before the bow broke (it was the upper limb that broke)
--Mark R.