HI, thanks for using healthcare magic
Pregnancy tests detect the HCG hormone. This hormone is normally detectable by day 11 to 14 after conception.
If the test was done too early then you would get a false negative result and it should be repeated in a few days.
With a history of a
vasectomy in your partner, it is not likely that you would conceive.
There are other causes of delayed periods such as :(1) emotional
stress or illness
(2)abnormal levels of
thyroid hormone
(3)physical illness
(4)high levels of a hormone called prolactin
(5)side effect of medication
(6)polycystic ovarian syndrome
If the pregnancy test is truly negative, then you may need to see your doctor for an assessment.
This should include physical examination and blood tests (hormone levels, thyroid, prolactin).
Imaging such as
ultrasound, may also be needed as well.
I hope this helps