Weight gain !!!

I went on the pill 'cerelle' that you take every day without a break around 3 months ago, in the past month or so I've noticed a dramatic gain in my weight I genuinely look fatter in myself. I've always been slim and now I starting to worry. People say it's not true that you put weight on when on the pill but it definitely has happened to me! I'm starting to go the gym more frequently now but is there any other tips anybody can give me or recommend a better form of contraception that worked for them after trying the pill? TIA!! X