Yes, the right arm is a bit limited space, isn't it? XD *giggles*
When in regard of small space, don't complicate things for yourself, it looks fine to me though.
The Collar one also look fine... but there is one awkward view.

Collar zigzag on viewer right looks fine. But on viewer left, I can see the different width of the lining, seems like on breast is smaller than on shoulder?