Did you have unprotected sex while you were "missing" pills?
If you had been back on your pills for at least 7 days before having unprotected sex, then there is a good chance things will be ok.
As someone else said if you want to delay your period, just skip the inactive pills and go straight on to the next active pack straight away.
Most pills suppress ovulation and while skipping pills can lead to pregnancy (even one pill) as you have been on them for quite some time, even if you stopped taking them now to try and concieve it might take a while to get back to a normal cycle and ovulate.
So there is to ways of looking at your situation - because of the hormones in b/c pills suppressing ovulation - technically the body thinks it is pregnant, so a test may be inaccurate, I would suggest a blood test from your doctor instead.