It can take multiple months, up to a year, to fully adjust being off the pill. So you should expect side effects in that time such as irregular bleeding/cycles, mood swings, breast tenderness etc, similarly to how you adjusted to being on it. It's common for cycles to seem regular for a few months before becoming irregular again, there's really no way to predict how it will be for you.
The only known form of birth control that has weight gain as a side effect is the depo shot/implant. It could be that it had nothing to do with your pill. Have you contacted your doctor about and investigated if you might be having some issues with your thyroid or something like PCOS? Depending on the age you started taking the pill, maybe your body simply matured into womanhood. Your body is still growing well into your 20s and you might not have even realised it. Many young adults don't realise how much less active and more sedentary their lifestyle becomes once they start their careers and your metabolism slows down with age. I could be completely wrong of course, but it's important to be realistic.
