You are very brave to take on such a large project for the first time doing leather work. Your lacing looks good, the cuts and stamping are good for your first project. I think you may need to pay close attention to the dampness of your leather when working, it is a balance of not so wet that the leather sprays water out when stamped and not so dry that you can not make an impression with the stamp, try dampening your leather with a sponge and wait until the color starts to change back to the way it was before you wet it, it should feel cool and damp, now keep that moisture content constant, as it starts to dry out dampen again and wait, this will help give smoother cuts and deeper stamp impressions. Practice, practice and more practice.