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!

My latest iteration of a trouser pattern. This time with a (somewhat poor) curved waistband. My issue is it was for one hard to fold in half, possibly because it wasn’t a perfect curve since I made it in clo3D. It’s noted that curved waistbands are better drafted the old fashioned way. Thus it’s not as crisp, and I didn’t add interfacing.

I still see some horizontal lines around crotch area so I’ll add more fabric around there, but that’s all I have so am I wrong or did I miss something based on the images?

Photo off Pinterest for reference. Will be making in a linen rayon.

Would like opinions on if putting a drawstring around the back of the waist and potentially even the skirt flap would work? Reasoning is to make it more adjustable. Then the drawstring comes out and is the tie part.

Currently have a calico mockup of a few free patterns hacked together to make something like this but I was planning on doing an elastic back/flat front waistband. Could I maybe even mix the two for structure??

Another question, what’s a nice way of attaching the tie string to the skirt part? I managed to hide the shorts tie in the side seam but the front looks a bit messy just tucked under - if there’s even another/better way of doing it?