Just really confused..

After my SO and I talked about birth control options, I started taking the birth control pill three months ago, and everything went fine the first month. The second month I got my period two weeks before my packet told me I would, and I felt crampy and bloaty the whole month. This month, the same thing happened. I'm confused and annoyed because birth control is supposed to regulate periods, but mine are still so irregular. Could it be my body is still adjusting?