What's wrong !!

So I haven't got my period yet my last period was in September at the lastest and I'm feeling really tired and I'm kinda sick like stuffy nose that's it sometimes headaches and sometimes I feel like I'm going to throw up everything grosses me out basically but I took a pregnancy test and it didn't say I was pregnant and the last time I had sex was with my ex BF in September ! Is the pregnancy test wrong!!!!!!!