Hey peaceandjoy, welcome to the thread! Buying fabric for immediate use is ok, sometimes you need something specific to tie together a bunch of randoms. We also do have a few exemptions like for travel or birthday.
My stash is also mainly small pieces and organization is always an issue. When we moved, I ended up with more fabric than I wanted because I just couldn't make any more decisions. I did give away tons, probably literally! I've gone from cardboard box storage to semi-clear totes, which are semi-sorted into colors or themes, and then I put on labels on the outside as well. Husbands tend to like big black costco totes which are too heavy when full of fabric for most of us older female types... My totes are about 30 pounds each full which is enough to make my grunt pulling them off the top shell.
About the weight and seams, those tiny triangles of Bonnie's can have almost as yardage much on the back as they do on the front!