Im almost 9 months postpartum, before ever getting pregnant my cycles were like clock work, every 27 days.

Now my period isn’t as predictable it’s usually still between every 27-30 days, but it’s not like before where it was every 27 days. I never know if I’m late or my cycle has just changed. I go to my doctor in 2 weeks so I’ll be asking her about it but curious if any one else has experienced this?