sore nipple question

I have never gotten sore nipples before as a sign of pms, the only other time I got sore nipples/boobs was April 2016 whenever I found out I was miscarrying. I have had really sore nipples now for two days but I took a walmart first signal test yesterday, that came out negative but then had an evap line a few hours later. Could I still be pregnant & just be too early?