The pill isn’t linked to direct weight gain (only the birth control shot is), at most it can hold water weight (which is temporary) or an increase in apetite whereby you can manage your portions. A lot of people blame birth control when it’s just their bodies changing and developing into adulthood. It’s normal to gain weight as you become older as you won’t be your teen weight your whole life.
If you value yourself based on a number on a scale and whether that increases I’ll tell you now that you’re never going to be happy. Look into body positivity, it’ll do you good x