3/4 DPO and sore nipples ??

Jessica
3/4 DPO and I have sore nipples... why ? It can't be pregnancy symptoms because it's too early for that ?  I never get sore nipple, only swollen boobs . I'm not 100% sure if I'm 3-4 dpo because the app said yesterday was my most fertile day but I had watery CM Wednesday and Thursday and dry cm Friday Saturday and again today so I'm guessing I ovulated early .