How Can Weight Gain With Stomach Bloating Due To Contraceptives Be Treated?

hey.. im 22 years old and last year i had surgery which was ovarian cystectomy for the big ovarian cyst that i had.. after that i had gnRH agonist for 6 months and now im on Oral contraceptives which my doctor said i should be taking lifelong until i dont get pregnant. The major side effect that i have been having is weight gain. I had stable weight gain of around 46kg for 3 years which was normal for me.. but now ive gained 10kg in since ive started the pills and im developing a huge belly fat.. i have been doing exercise (30 mins treadmill everyday + crunches) and trying to control my diet however i cant get rid of belly fat... can u please tell me wat to do it looks horrible plus i ccant sstand the comments i get from other people about how fat i am nemore..