HONESTLY, I think the hype about weigth gain on bc is a joke. People use the myth of gain as an excuse to overeat & then blame it on the pill. I'm not saying that some peoplen't sdon't gainw eigth from BC, they do, but thats either only from water retention/over eating. BC messes with your hormones & can cause your hunger to increase/decresease, but it DOENS'T just plop pounds onto your frame. It's up to you to have the willpower to coutneract against the new cravings.
I say this from experience. I started BC recently, I neverw anted to do it for years cause I was PARANOID about weight gain. I'm an Anorexic, have been for almost 11 years now, & my doctors wanted to see if they started me on Yaz, if it could cause me to menstruate (I haven't had a rela period in over 7 years due to my ED). I was so scared about gaining weight that I protested, but finally gave in. I haven't been on Yaz very long (less than a month), but I've actually lost 6 lbs. Now, that could just be due to my eating disorder & have nothing to do with the Yaz, but still. I don't have an increased appetitie or any fluid retention & my only side effect is acne (which sucks because in 21 years of life I have never EVER had acne, but now have minor acne...but still.)
Anyways, don't be scared about the weight gain prospect. Just take the pill, & monitor your weight. Don't obsess/restrict to make up for it, just eat NORMALLY. Small portions, healthy foods, get exercise etc. Chances are you will not gain weight. Yes, everybody reacts differently to meds, but honestly, most girls I know don't gain weight from BC unles they start eacting obscene amounts of food claiming an "appetite increase". If you do experience an appetite increase, make up for it will HEALTHY snacks like fresh fruits/veggies, & you should be fine
ALSO, when a medicine lists it's side effects ont he box, you should know that they are requireds to list EVERY reported side effect from anyone. Which means one lady in Alabama might gain 10 lbs, & they have to list it as a possible side effect. It doesn't mean it will happen to you. Don't worry to much, just act normally.