Some shopping excursions are like that. A second trip to different stores (or the same stores once they've got more winter stuff in) might be worth your while, or just ordering online if any of the manufacturers or retailers you like have online shops. Or if what's available isn't
too bad, maybe you could just buy a couple pairs as a stop-gap until you're in 16s. It's probably not much consolation, but FWIW I've got a quite noticeable amount of varicosity on my legs, and I'm in my mid-20s.