Pregnancy test ?

Okay so question. I had sex on the 1st ( using protection). Around the 13th I was supposed to start my period but never came. So I took a test on the 20th and 22nd.. both said negative. But I think I ovulated late around the 17th when I was supposed to ovulate dec 24th to like dec 30th .. anyways I guess my question is .. could the pregnancy test be wrong since I wouldn’t have enough “levels” to detect? Btw rn I’m having light brown discharge and some cramps