Why does my left breast feel heavy? I am not pregnant and my last period was about two weeks ago.

Other symptoms? Pain, drainage from nipple, change in skin, lumps or bumps you can feel that are not normal for you? If yes to any of these then need evaluation. If not, wait a menstrual cycle or 2 and see what happens. If left breast still feels different then see doctor for evaluation. Hope this was helpful. Best of luck. Dr R.