now have about 3 garbage bags worth of mixed fabrics. ...
does it fit the sleeve and everything? like, is it comfy?
Mine is pretty darn comfy... that's why I cut the sleeve on the bias. It keeps it from binding around your arm. You also need to put the dart at the top to fit the curve of your shoulder (unlike the knit that will just stretch around the curve).
Cut the sleeve top a little taller than you'll need it to be, sew up the underarm seam, put the sleeve on your arm inside out, pinch and pin the excess to fit around your shoulder up to the neckline and then stitch the dart. Trim the excess fabric.
Lucky you with all that fabric! What a treasure. It's so fun to pick odd-ball things that actually look really cool together. I bet you have tons of potential in those bags.