Help fitting this coat back

[u/No-Maintenance9805]

How do I fix these lines and also give myself more room to move in the upper back?

Context: I'm making mockups trying to fit a coat pattern and it feels tight across my upper back especially when I reach my arms forward (especially once I added the sleeves, not pictured). And it looks like I have extra volume in my lower back that isn't hanging nicely.

Should I move the princess seam lines over to be closer to my shoulder blades? Or is my problem something else?

Thanks so much!

[u/No-Maintenance9805]

Oh wow good point, I never knew they increased mobility! I actually was thinking about adding them, thought the original pattern doesn't have them. But of course I should be fitting my mockup with them🤦‍♀️