What are my chances?

I am a relatively healthy girl (I smoke) and I've been on birth control for 8 years, February 1st-February 5th I was on amoxicillin for an illness. Partner and I had sex twice during antibiotic. Then February 6th-8th I was on the sugar pill week, and last night I forgot to take my new pill pack. What are my chances of pregnancy? I'm afraid to take birth control in fear I am pregnant. Thank you!