Late period and EBF

Has anyone's period came back fairly early even tho your ebf? I stopped bleeding between 2/3 weeks after having my son. Then when he was between 7/8 weeks I had what I believe was a period for 4days which is how my periods were before I got pregnant. Well according to glow I should've started my period a week ago. Is it normal for your periods not to come back on the cycle they were prior? Or should I be worried that I haven't had a period yet?