Afraid of birth control

I have a fear of birth control. It's not a rational fear I know. I will be getting the pill and I need some reassurance of a few things from some of you ladies on the pill. Did you gain weight? Did you get extreme mood swings of any kind?

I'm already suffering with weight gain and bipolar disorder so I don't want to add to my plate of issues.

Any help or simple reassurance would be greatly appreciated. I've never taken birth control.