Can Estelle Cause Weight Gain And Heavy Bleeding?

Hi, I m a 15 year old girl and I weigh about 55kg. My height is just under 1.60 metres. I m currently taking the contraceptive pill Estelle to cure my acne. I have been taking this for about 4 months. I have found that my periods have been REALLY heavy since starting to take it and I have started to put on weight (about 5kg recently). I eat a pretty healthy diet (6 glasses water a day, 5+ fruit and vege etc) and I excercise 5 times a week. Can you tell me why I m putting on weight and why my periods are so heavy? thanks :)