I think there's no adjustable lumbar in the ST seats. Pre-production models had 8-way Recaros with lumbar and extensible thigh support, but the production car has 6-way seats. Had to cut something to meet a price target, I guess.
Of the dislikes I've seen, most seem to involve the width of the side bolsters, rather than the seats.
I'm even shorter and heavier, and certainly wouldn't describe the seats as "painful". The seat's deeper than I was used to. But I don't find it uncomfortable -- just unusual on first acquaintance. Seemed pretty normal after a few drives, and I like not sliding around the way you do on a flat, wide, seat. Jury's still out on long endurance drives, where the lumbar support might become more important.