Thanks for the query.
While using contraceptive
pills side effects like menstrual irregularities can occur.
Some women may have hypomenorrhea
Some women may have absence of periods also.
For more details : http://srsree.blogspot.in/2013/11/general-guidelines-of-using-combined . tel
If you used the pills as per the guidelines, the possibility of pregnancy is less.
Go for blood test
for pregnancy test once.
If the test comes negative, the possibility of pregnancy is less.
You can continue with your tablets.