I don't think this is something to be overly concerned about. Maybe AMCAS calculated your sGPA as 0.0, but that is different than having a 0.0 or similarly super low sGPA because you failed or earned D's in science courses. I also don't think it's a concern that you have several semesters of not taking any science courses, because as long as you have taken the required courses (and potentially some of the "recommended" courses) and done well in them, you really have nothing to worry about assuming you have everything else in order (competitive cGPA, MCAT, ECs, etc.).