I am 9 days late.

I have a very fixed cycle since more than a year now, but this month my period still hasn’t come. My period usually is 1-3 days late but now I am on my 8th day late and have no period symptoms except acne which I generally have everyday for the past years so that is not a valid symptom.

I am a virgin so I certainly am not pregnant.

I am a bit worried because I never had such a late period. Does gaining weight cause changes in period? Because I have gone from 91lbs to 99lbs in less than a month so maybe that plays a role.

What do you think might have happened? Could it be any other reason?