You had unprotected sex, you could indeed be pregnant.
When should you have gotten your period?
If its late, you can test now! its not early to test at all.\
On pregnancy test boxes it says the earliest you can test is 4 days before your expected period.
Take a home pregnancy test, with the first morning urine like it says on the box,
and find out. Then, if you are pregnant, go to your doctor and he or she will do a blood and urine test to make sure you are pregnant.
If your not pregnant, get back on birth control and USE CONDOMS aswell.