If you took your pills correctly then there is near to no chance. There is a tiny tiny percentage of people who have a gene mutation which stops BC from working, but if someone had that, then it would’ve never worked in the first place, so they wouldn’t get side effects or a withdrawal bleed (“period”) etc. If you’ve already experienced the affects of your BC, you can rule it out, so taking it incorrectly would be the only way for it to stop working.
If you have a heavy bleed, it is unlikely you are pregnant. That being said, you can still bleed in pregnancy, and lack of bleeding DOESNT mean you are pregnant. It is common for bc to lighten or stop bleeding altogether. The only way to know for sure is to take a pregnancy test, but that is not needed if you take your pills properly.