Oligomenorrhoea. My periods are delayed.

I have this oligomenorrhoea since the starting of lockdown , i guess since March. My periods are delayed. So i got a check up done if i have PCOD , so my USG was normal and i was not diagnosed with PCOD. Last month i was not having my periods at all so i went to the doctor , he gave me krimson 35 . And after some days i had my periods. It's like every month there's some problem in my menstrual cycle. I would like to mention that i was 43 kgs before march but i have gained 10 kgs so i am 53 kgs now. I do a bit of brisk walking in the evening . I sleep on time and get up on time. Please help me with my problem 🙏. I don't know what is wrong in my routine that now it has become the story of every month that my periods are delayed.