pregnant symptoms

So recently (past 2 weeks) my nipples have gotten really big and swollen, to a point where my husband thought I was going to explode! I've been feeling extremely tired and nauseas, have slight backache and headaches, been getting a random intense burning feeling in the back of the inside of my throat, down my neck, and I have to pee litteraly every 20 minutes. I took a pregnancy test about 6 days ago, and it was negative. Could I still be pregnant? I don't know when I'll get my period because I don't have it every month and never get symptoms of periods. Been TTC for a long time now, with no luck!