Birth control? Periods? Help pleasseeee

So I started the pill a two days after my first period (OB said to) well I was supposed to start a period yesterday according to my app and it’s usually never been wrong so I’m just confused when I would start? OB still said I would have a normal period. Iv also had cramps all day yesterday and today like as if I was going to be starting my period!

Also this is my first time ever on birth control!