Skipped period - but not pregnant

Hi guys! To say I’m overthinking this is an understatement, I will preface this by saying I have seen to see my doctor today and we are doing a full blood panel and hormone work up to see what’s going on. Love her. Anyways, I am 28f and have never missed a period. Ever. It’s not pregnancy because the last time I touched a man was 6months ago - and I have had a period every month since then, and I have had no symptoms of pregnancy. I’m usually pretty regular can fall a day or two either side of a 26-28 day cycle length. Currently a week late. With none of my normal pre period symptoms - sore boobs, emotional and food cravings. It’s just stopped. And I’m super paranoid about being perimenopausal as I’ve heard term being thrown around a lot lately. Also I’d like to note - my stress levels are at an all time low (aside from this little issue) What could this be?