Hello,
Pregnancy test kits are basically qualitative kind of test which just tests presence of hCG hormone in the urine of pregnant woman because this hormone is only produced during pregnancy among women. But this pregnancy test depends upon the particular level of hCG in the blood. So sometime it may be possible that it can give you false negative results during early days of pregnancy only because of un- sufficient level of hCG to make test positive. So it is important to get serum HCG test done which is more specific than urine for pregnancy test. If pregnancy is ruled out and periods don’t come a step wise evaluation would be required to find out the cause of delayed periods.
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 and please do keep me posted on how you are doing.