Re: On the pill but had unprotected sex....
Since you're on the pill, it wasn't unprotected and therefore the PlanB was totally unnecessary. Women on the pill frequently have sex without condoms (in fact that has always been one of its big selling points ever since it was invented). Although its not 100% effective against pregnancy, it is very high up there like 98% when taken correctly (which you have).
You have nothing to worry about except some major side effects from having taken the Plan B on top of the pill. None of your upcoming side effects are pregnancy related, they will all be due to the mega dose of hormones that you just ingested.