Hi,
I understand that you have taken birth control irregularly. Maybe you did not have the complete information about how they act and the need to take them regularly and preferably at the same time. Even then the chances of
pregnancy are low if you have occasionally missed a pill.
However, since you have used
contraception irregularly and sometimes have been off contraception, pregnancy cannot be ruled out. If you are having pain and cramping now, wait for a few one or two days for the periods to come. If still no period, better have a pregnancy test done using a good kit and if positive go for a
blood test or
ultrasound examination for confirmation rather than taking series of tests.
Remember that
stress causes missed periods. So, stop taking a stress of it.
Also regarding the pills, they must preferably be taken at the same time each day and if a pill is missed, take it as soon as you remember, preferably within 12 hours of being missed and take the next pill when it was regularly scheduled that may be the same day. If more than 1 pill missed, keep taking the pack but use some backup method like condom for next 7-10 days to prevent pregnancy.
Hope I was able to help you.
Have a nice day.