I have been feeling nauseous, the test is negative

So there is a chance that I think I am pregnant because for a week now I have been feeling nauseous after I week dinner. Heres the thing though. On Dec 2 I went to the er for kideny issues and they drew blood and they checked my HCG level and it came back negative. Does that mean I am not pregnant? Also I went back on the 19th of Dec did the same thing and my HCG was negative again. My periods are irregular due to having an cyst on my cervix which they caught when I was 15 years old. I am 27 years old. I had my period last month on the 18th or the 19th it's in my calendar which lasted 4 days. A week or so later I took a pregnancy test cause I kept peeing frequently and it turned out I had an uti and my pregnancy test came back negative. I had the same issue 2 weeks ago did the uti test and I had an uti and took a pregnancy test came back negative. I am freaking out. Please help me.