I would suggest breaking this into three separate sections in thinking about how to model it—the body, and the two strap halves.

Then, realize where you have symmetry: the body itself is *overall* bilaterally symmetric both side-to-side and top to bottom on it's core form. Sure, it has sub-features that are non-symmetric, but you can work down to those *after* you've dealt with the overall form.

The straps are symmetric, side-to-side.

From there you have a much easier modeling task, you in essence need to just resolve 1/4 of the body, and 1/2 of the straps.