As you got two negative pregnancy
tests, then it is unlikely to be pregnant. You are suffering from irregular delayed period which is called oligomenorrhoea in medical term.
The causes are ovarian cyst
or PCOD (most common), hormonal
imbalance, stress/ anxiety, thyroid problem, wt gain/extreme loss, irregular eating habits, psychological factor etc.
You may require some investigations to rule out underlying pathology through USG pelvis, thyroid profile & other hormone assay, blood sugar & prolactin
level etc. A urine examination is also needed to confirm any type of urinary infection. Consult with your doctor and take suggestive measures.
Avoid stress / anxiety, take healthy diet with iron supplements
, eat more fruits & vegetables, drink plenty of water or juice, control body wt by regular physical exercise and maintain genital hygiene properly.
If you need further consultation with me, then you can visit http://www.healthcaremagic.com/doctors/dr-soumen-patra/63326.
Take care yourself.