Thanks for your query.
Since this period was delayed, and the pattern was not like your normal period, you should be doubly sure .
Sometimes, a miscarriage
or an ectopic pregnancy
( pregnancy outside the uterus
) presents in this way.
Also, rarely, a woman bleeds but still pregnancy is ongoing.
Since one HPT is already negative, I suggest you consult a Gynecologist who would examine you and suggest an ultrasound/blood pregnancy test for confirmation.