...caused this to cut into my armpits very uncomfortably..

Otherwise, it would be soft against your skin. Wide set straps have restricted stretch and are only partially adjustable. As with other styles of this brand, the straps feel very short. Seamless cups are thin foam, give nice lift without pushup padding; simply lined enough for modesty. Cups are true-to-size for Le Mystere's sizing range. Band is a snug true-to-size fit.

It's probably a better fit for someone wide and somewhat shallow (or tall roots?) and also even to full on top and/or high set.