It is less likely that you could be pregnant as both the tests are negative.
The delay in periods as well as the symptoms you are experiencing might be due to hormonal
I would advice you to go for a sonography
of pelvis, and a thyroid
function test to know the exact cause for delay in the periods.
Meet your gynecologist with the reports,and she would advice you on further medication to resume the periods if the reports are normal.
Dr. Om lakhani