Plan B affects women on the pill in certain situation? now?

Birth Control and Plan B
I am on birth control but I know there are some factors that affect the effectiveness such as use of antibiotics or not taking the pill the same time every day. Therefore I usually use condoms as well. Unfortunately I ended up having unprotected sex one day and was worried about my birth control b/c I had taken it late a couple of days. So I took a Plan B pill. I continued taking the birth control as usual. 2 weeks later I had sex that was protected but there is a minuscule chance that the condom broke. If it did fail should I be worried? I know the plan B messes w/ the cycle so I must use back up. I am concerned although I don't think it broke but the chance is still there. If I have been taking my birth control as usual after using plan B how concerned should I be? Should I take another emergency pill? I don't want to take another one because of how it changes the cycle and then I will have to be worried for ANOTHER month if the condom breaks. My period is due tomorrow or the next day but I know Plan B changes it should I wait until it arrives or go ahead & take another emergency pill?