could I be pregnant?

I’m on the pill and I make sure to take it everyday at the same time (maybe an hour late every now and then). I had unprotected sex with my partner and only one day (last week) I forgot to take it so I doubled up the next day as instructed. Now I’m spotting brown/pink discharge and i feel nauseous everyday (my period isn’t supposed to start for another two weeks). Could I be pregnant or is this something that happens every so often while on the pill?