Late period? Advice?

So I’m 15 and about 5 days late. I’m usually quite regular on my periods even though I can be up to 2 days late/early. i haven’t had sex at all and I don’t really feel the symptoms as severely as I usually do, I’ve only had some very very slight back cramping and cramping round my front (these are my normal symptoms but I usually get them more severely). I’m around exam time and some girls have told me that stress effects periods and my friend even missed her period for 2 months? But anyway can somebody help me out as this has never happened and I’m worried