@jespah,
Sore nipples can sometimes be a sign of pregnancy, but everyone has different signs that may indicate pregnancy, from fatigue to nausea and others - and some don't get any symptoms at all! Of course your best bet is a pregnancy test. If you're really anxious, a blood test can get results only a few days after conception whereas for the regular pee on a stick kind you'll have to wait until a few days before your first missed period for accurate results. Good luck!