Because you bind off in stages to shape the shoulder, you do get a bump or step in the shoulder line. These steps should match on the fronts and backs. You can seam by lining up fronts and backs with the right sides or public sides of the knitting facing each other and sewing a seam in a straight line from armhole to neck edge. Don't follow the steps of the bind off, seam in a straight line. You can also do a mattress stitch seam on the shoulders if you follow this video
Glad the neck and shoulder shaping worked out.