Hi,
Welcome to the ehealthforum and I am really glad to help you out. These can be the symptoms of pregnancy.
Ideally the urine for pregnancy test should be done 1 week- 10 days after missing your periods. You can repeat the test after 1 week of your missed periods date or get serum HCG levels checked. If pregnancy is ruled out then please consult a gynecologist and get the other possibilities for your delayed periods ruled out.
It can happen because of hormonal imbalance, increased stress, eating disorder, increased smoking, alcohol or caffeine use and medical conditions like PCOS, fibroid, polyps and endometriosis.
It is very difficult to precisely confirm a diagnosis without examination and investigations, and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.