bc and weight gain

Hey girls I've literally been a size xs all my life and now I'm 22 and have been sexually active for a few years. I started taking bc to be safe and for weight gain. I've taken the progesterone pill for over a year, no weight gain, I then tried the shot over a year ago that was unsuccessful so I've been using microgynon 30 for half a year and still unsuccessful. I've tried gym, eating more, apetamin, appetite enhancers everything