Ladies I'm two days late for my AF and I keep getting negative tests. I've also been having lower…

Ladies I'm two days late for my AF and I keep getting negative tests. I've also been having lower back pain and mild cramping for a week. And having to pee very frequently. And have been spotting once a day for three days already the first day it was a little pink. The second day I had this really thick eggwhite discharge with a little blood barely noticeable, and today it was just brown. But still no periods. Could I have conceived? Or what's going on?