Is the morning after pill effective while on period?

So Saturday night I had sex with my girlfriend wearing a condom while she was on her period (get over it it's not that gross). Unfortunetly the condom broke and I finished inside her. And I know you can still get pregnant while on your period so the next morning (Sunday) she took the morning after pill. This is also the day that she finished her period. So I'm not 100% sure if the morning after pill was still effective or not. Because today (Wednesday) she complained about having to pee every 20mins which is an early sign of pregnancy. However she also just started a new medication that can make er urinate more frequently (Zoloft) and today is her second day taking it. So the bottom line is, would the morning after pill still had been effective when she took it? Because it wasn't even 18hrs after inter coarse that she took it. And I'm really freaking out thank you in advance