Another answer, now to the modified question.

I attach a picture of central part of your geometry with numbers of elements and tangents. There is a vertical line which are line of symmetry. If you want to have symmetrical mesh then you need to have all geometries to be also symmetrical. However, for surfaces 1 and 4, for example, the lines 32 and 34 are symmetrical for vertical symmetry line, but the lines 6, 35, 42 are not symmetrical to 7, 38, 39. The are directed in non-symmetrical directions.