Periods After C section. Be reason?

Hello Doctor! It's been four months that I have undergone c section..on July 31st surgery was done and got my periods on September 11th..that means bleeding stopped after few days of surgery and started like period on september 11 th again after 18 days that's on sep 28 again it started like period...got confused if it was normal bleeding or periods but doc stated that it was period for me and I got early ..again I got periods on 24 October..so thought cycles got normalised but this month it s delay of five days still I did not get periods..no sexual activity. In between .what would be the reason for my periods delay i regularly get my periods...do I need to check my thyroid? Coz I do have that problem but am using medication for it so thinking it's under control i checked it before pregnancy..or anything might be reason? Waiting for responses Thank you