Climbing webbing is good for climbing, but not for hanging a hammock.
Typically, climbing webbing is designed to stretch to absorb the impact during a fall. So in a hammock hanging scenario, stretch is to be avoided. You may have issues after a few hours in the hammock, with the hammock ending up touching the ground. ymmv.
Several different ways to sew your webbing. A box stitch with with an x thru it is generally good. Repeated zig-zags work, too. Pick your poison.
yours look fine, depending on what type of thread you used...100% polyester is the preference here....not that other types won't hold, just preferred.
Ambulo tua ambulo.