The thing about ball pythons is they all seem to have a different look kind of like a finger print, just a lot of features are the same which makes them the morph they are. Some pastels may seem brighter then other pastels. Some brown out more then others. It is this reason that a lot of people mistake other morphs for normals or hope that their normal is a different morph.
I am not saying that your particular female does not have chocolate in her as I am not an expert but breeding her again may prove her to be or not to be chocolate. But out of the clutch you just produced and none of them coming out chocolate may be a hint that she is not.