I was put on amoxicillin last Friday and took my last pill this Friday. The Thursday before my last amoxicillin pill, I started my birth control, Sprintec. My boyfriend and I started to have sex last night, lasting hardly 5 minutes because I remembered the amoxicillin can affect birth control. I had only been off the amoxicillin for 2 days. Do I need to be worried and take further action?