Is this normal? I'm a FTM

Sadie

I had my son 2 months ago, I breastfed for 2 weeks and then had to switch to formula. I started my first pack of birth control pills 3 weeks ago and yesterday was supposed to be the start of my period days. I haven't started my period though. Is this normal? Should I call my doctor? When should I expect my period to come back? Thank you in advance! I'm a first time mom and have no info on this!