I Am 20 Years Old And 100% Not Pregnant But
You can go for investigations.
Thanks for trusting us about your healthcare.
I have gone through your history and understood your concern
If you are not pregnant, delayed menses could be due to hormonal imbalance caused by so many reasons like stress,thyroid, PCOD.
So you should get your Haemoglobin, thyroid profile and pelvic ultrasound to rule out the possible cause of your symptoms.
Hope you find it useful,feel free to ask more information.