Also look for any action requiring you to hold down a mouse button while dragging (like most 3d software do for moving verts or objects) and try to get rid of it.

Blender has a very clever legacy input scheme (quite unusual for people not familiar with oldschool command-centric CAD) revolving around tapping a key to initiate a command like Move, followed by moving the mouse to perform the action (without any button being held down), and then confirming or cancelling the action with another tap of a button. This coupled with the fact that such a Move action doesn't have to start anywhere near the element being moved but is instead performed relatively to wherever the mouse cursor was located when the action is triggered makes it way easier on the hands than having to precisely grab, hold and drag a manipulator like Maya or Max require, and it's also objectively faster since it involves less mouse travel. Once you try it there's really no coming back, it's just that much more pleasant, streamlined and easier on the hands.

This could probably be applied to navigation too, but I think that using this kind of lightweight input scheme for object manipulation alone could already be a significant improvement for your hand pain.

Since you already have the sewing pattern, you could try the Cloth modifier. Trace the two shapes with splines, apply the Garment Maker modifier or Subdivide set to Delaunay, copy (edit: reference) and arrange very roughly like shown by Eric, define the connected seams and simulate in place with some internal pressure. If you want the surface bump as geometry, you can Skin Wrap that high poly geometry to your flat cloth pieces before simulating (but if you use bump/normal/displacement maps that's not really necessary).