Negative tests, but still feel off. Help!!

I ovulated sometime around March 30th, give or take a couple days, and had sex on April 3rd. I’ve had some long cycles, but I’m about 2 weeks late for my period! I’ve been under an unusual amount of stress, but am trying to relax so my cycle can continue. I am taking tests every couple of days to make sure I’m not pregnant, but I’m thinking that maybe my hormone levels would be too low to read? I use First Response so I know I get reliable results, but my racing mind doesn’t trust anything 😂

Do you think that if I’m late by 2 weeks, a negative reading is accurate? I’ve been feeling some nausea and dizziness lately and can’t help but associate that with a babe on the way!