I had my regular periods in August, September, and October. The last time I had some sexual activity was in August, that too with protection and there was no penetration. After that I have had my periods regularly. Last period was on 17th October (Day 1). I was expecting my period to arrive on time. But it has not come yet. I have had another sexual encounter (protected but no penetration was possible) during November while my periods was already late by 6 days. So why this late period? I travelled 200 kms daily in the last week of October for a period of one week. Then after, I ate a lot of food outside. And further, I have gained weight around 4kgs. Please suggest.