Is breast tissue supposed to be symmetrical ? meaning, when i do a bse, the "landscape" of the tissue of my left breast pretty much matches the right

Generally, yes: Most women have fairly symmetrical breast tissue architecture from one side to the other. It is very common to have mild asymmetry in terms of size. It is even common to find different architecture within different areas of the same breast. Your best value in doing BSE is detecting a difference in any area of the breast compared to previous BSE's.