I finished my traditional English briefcase yesterday. As you can see, I made a strap for it as well. This is only my 3rd bag ever, so I'm pretty happy with it (I'll be keeping this for myself). This is was really enjoyable to make.
The biggest headache for me was learning how to use a manual splitter to split down the gusset strips. Definitely a learning curve. I started with a cheap splitter, which worked horribly, and eventually purchased a good one.
Fantastic, especially considering that's your 3rd bag ever! I noticed you stitched two seams on the shoulder strap. did you use two strips of leather glued on the flesh side?
Wow!!!! Great work, it is truly beautiful.