So confused

So my last period started February 13 & ended the 18th. I have took pregnancy tests & they came out negative.. I’ve been having the WORST breast pain ever all throughout the day , I get very nauseous throughout the day , my nipples itch sometimes , I’ve been emotional and been getting grossed out by food lately. The nausea is almost as if I had a bad bad hangover. If I let myself throw up I would’ve but it tends to be at night so I try to sleep it off. I’m also having bad back pain mostly lower back pain and been having a stuffy nose and sneezing a lot. I went to the ER because I’m out of state and don’t have insurance out here yet to see if they can do a blood test and they didn’t but they did tell me test again in 1-2 weeks. What are y’all thoughts? If I’m not pregnant what could this be .. I’m a very healthy person as well as my family . I feel as if I’m one of those people who’s hcg just isn’t picking up through a test but how likely is that to happen. Please help.