Okay, I modified my Accidentally On Purpose. It's still not perfect, but it's good enough, now. Here're the results:
Original shirt, modified shirt:
Original neckline, modified neckline:
I shortened the shirt quite a bit (it was even longer in the back, originally). I also changed the neckline, because with the bind-offs instead of decreases, it looked too choppy. So I did slanting decreases on both sides of the neckline instead, and made the shoulder pieces a little wider so they'd be a little sturdier. The large size fits my bust, but not my shoulders, which resulted in the first shoulders being waaaay too wide. They're still too wide now, but a did a few decreases on the outside, too. Not perfect, but it looks like it fits a little bit better than my first go around.