Female respondents, female staff members, and male respondents who enjoy giving women lingerie as gifts—please help.

Do you know of any stores that carry lots of panties with a relatively narrow crotch? At the moment, I’m using lingerie from Wacoal’s AMPHI brand (I think?). They have bras in a series that fits me perfectly, but I still haven’t found panties I really like. (If bras come in so many sizes, why are panties only available in M or L ; ; ) I use panty liners, so if the crotch is the wrong width, the liner bunches up, and the raised edge digs in and feels prickly and uncomfortable. Pads and the like also bulge in the middle, which is uncomfortable too. If anyone has had a similar experience and found a physical solution, I’d be grateful if you could share that as well. (I think it may be because the width between my thighs is narrow, but maybe slimming down my thighs could help…?) Sorry for bringing up such a sensitive topic, but I hope I get some answers!