Did you have unprotected sex since going off birth control? If not, it is highly unlikely that you are pregnant.
No form of birth control is 100%, but I never had a problem using condoms when I was trying to avoid pregnancy. Unless the condom broke or something, then yes, you could be pregnant.
It can take awhile for your cycles to get back to normal after stopping birth control pills. My first cycle off the pill was 35 days. I've known other women to go a couple of months before getting their periods again after stopping the pill, while still others go right back to 28 day cycles. If you were regular before the pill, hopefully your cycles should regulate after a few months. By the 2nd month off the pill, my cycle had gone to 30 days and from then on, it was 27-28 days.