Well ... I don't have those shorts either, but I've never known a pad to "break in." They will break down over time, but they won't become comfortable if they weren't to begin with, IME.
It does look from the photo that that's a very thick pad. Compare it to the photo of the pad in the Neo Power, which still looks kind of thick but rides nice and thin.
I'm 5'3," 120# and take a L in the LG Neo Power, so I would assume these are sized similarly. You might consider trying a L if you can exchange them, but it sounds to me like the pad is just too thick for you.
Speed comes from what you put behind you. - Judi Ketteler