Period is late by 3 months? :(

Kris

Ah, please tell me someone will see this! So I got my period 3 years ago, and it was unstable in the beginning but eventually balanced to one week a month, and it never ever skipped a beat for 2 years, ever, but my last period currently was August 9th-August 13th

I should have had 3 periods since then, but I haven't, no cramps or symptoms like I usually do. I'm a virgin, what course of action should I take?