Please help!!

Imogen • 💟💟💟
Okay so I'm 15 and I starting the pill in a week, I've heard that it can make you gain weight and no girl wants to hear that there's a possibility she'll gain extra weight. My mother was on it for acne (the same reason I'm going on it) She assures me that I won't gain weight as she didn't. My question is; if she didn't gain weight when she was on it will I when I go on it?!