Yeah, it looks really close to where I think you'd want it to be. Just needs a bit of tweaking.
And you're doing really decent work with just the line and curve tool on a mouse! If anything, making liberal use of layers and carefully erasing bits of the line to create thinness is another way to get that effect.
It'd probably be best to pull up multiple references to look at if your current reference is distorted.
And for the arms and shoulders, the easiest reference would probably be just looking at yourself in the mirror doing that and noting how much of them are visible from that pose.
Shirobako is top tier and among my personal favorites as well, so I have to applaud you for taking a step further and actually creating content for it, haha.
If you're looking for suggestions, I have a few:
- For Aoi, since she's your waifu, you could probably maybe do a POV shot facing down on her on the bed from the chest up with bedroom eyes.
- For Shizuka, cowgirl with hand holding and fingers interlocked seems like it would fit your description somewhat. She really does deserves some tender loving.