I realized that I'd tilted my head to the left to look down her shirt straight on

Lol, I've tried to do the same. I got v. excited in Photoshop last night when making my header, because I had to actually draw her cleavage (as all the posterising and thresholding made the lines almost disappear).
Then her jawline got fucked and made her look like a frog wearing a turtleneck. Trying to fix that was frustrating.