Probably a stupid question Sewing Machines Parts and Sales in Los Angeles

Why do the women’s and misses pattern sizes only go down to a size 6 or 8 at the smallest? I’m a size 0 and it seems like every pattern I see in stores or on the butterick or simplicity website are like that. I’ve found some that have the inches at the bust/waist/hips and they seem like the standard US sizes that I recognize, but maybe I’m reading these wrong? The only patterns I’ve used thus far were either free or one-size non-apparel patterns. Does anyone on here know a brand or website (free is possible) with patterns in a small or petite size? I’m still relatively new to sewing and the stores around me don’t have a lot to choose from as far as patterns go.

Also, the cotton fabric they sell in massive quantities and a variety of prints that’s kinda thin, is that just for quilting and stuff or can it be used in apparel? It seems too thin, but I guess maybe you could line it?