sore nipples! period or pregnancy symptom?

Hey guys! I was supposed to get my period yesterday - and I'm usually a few days off so I'm not surprised, but I just realized that my nipples are extremely sore to the touch and I've never had that before- and my boobs are so big! It could totally be a period symptom but prt of me thinks it could also be a pregnancy symptom. What do you think? Have you experienced this?