welcome to HCM.
If you did not intercourse,then there is no chance of pregnancy
. You also got negative test.
There are several reason of delayed period like hormonal
imbalance,thyroid problem,ovarian cyst
,psychological upset etc.
So do a USG lower abdomen and hormone profile (TSH,LH/FSH etc).
Check those results and consult with gynecologist.
Take healthy diet,do light exercise,avoid stress and need proper sleep.