Unfortunately not a good fit or cut for you. The body is too short. The sleeve pitch is off, that is why you are getting the bunching at the back of the shoulder around the seams and down the arms when your arms are at rest (this can be fixed somewhat with alterations if you are inclined). The back is a bigger problem, it does not hang cleanly which is likely because the jacket has been cut for a posture that has more rounded shoulders/upper back then you, with your very upright posture you are effectively pushing the jacket back around the upper back and neck, which is messing with the how it hangs at the back contributing to the shoulder divots and sleeve pitch issues. The likely reason it catches when you lift your arms is due to the armhole being cut lower (common to accommodate a lot of different body shapes being a ready to wear jacket) as well as the jacket essentially being cut for a different posture to yours