Greetings and thankyou for using justanswer,
You need not worry as such about the periods.s you already told that you had a lot of stress in the past few months.There are some common causes of such delayed or absent periods and the tress is a very common factor.
The common causes are stress, anxiety, emotions, pregnancy, thyroid abnormality, pelvic infection, pcos, menopause, bc pills, etc.
As per the symptoms , it is likely that the stress in you is causing such absence of period.Just try to relax and you will be alright.
Though the urine home pregnancy test can be false negative in early cases of pregnancy due to low levels of hcg in urine and in that case you should repeat the test after a week.The blood hcg test or uterine sonography are more confirmatory test for pregnancy.
The other causes should also be ruled out after consulting your gynaecologist.You should have the relevant investigations done like pap smear, uterine sonography, thyroid abnormality, blood counts,etc.to know any abnormality.
Let me know if you have any doubt.