Heavy bleeding 5 days after taking morning after pill

I had unprotected sex 1 day after I finished my period and took the morning after pill 43hours later. I started light bleeding (spotting) only 5 days after taking the pill, but the next day it got a lot heavier. It feels like my normal period except without the excessive pain. How long will the heavy bleeding (or any bleeding) last for until I start my actual period? I'm really worried, please help!