Is There A Chance I Could Be Pregnant? I Had

Is there a chance I could be pregnant? I had a period on October 1. I was started on 2 antibiotics on October 15 for h.pylori. I missed 3 birth control pills October 14, October 15 and October 16. I had sex on October 16 and October 17. I have had light bleeding since October 17 and have still continued to have sex.