Help need advice/opinions

I ovulated around the 19 , not exactly sure , my ovulation symptoms were noticed after that day(tender tingly breast , discharge wet and watery) this app says i ovulated on the 17 😩🙄 I’m confused . I had sex the early morning of the 20 around 4 or 5 am and i was UNPROTECTED. Starting last night i have been extremely nauseous, i woke up the morning nauseous and somewhat tired . I have had cramps but they come and go and are slight and my breast have been tingly and itchy. Could i be pregnant? I’ve been using cheap dollar store test and getting BFN . Any advice ?