Late period

I'm 18 and have had my period since I was 11. It's never been overly regular and usually varies between being on time and maybe a week late. Currently it is two weeks late which is a little out of the ordinary. I'm a virgin so there is no chance of pregnancy and I'm not stressed either. Why might this be and should I be worried? Could it be due to unhealthy eating over the holidays? Thanks for any help! šŸ˜Š