6 days late - brown spotting

I’m 6 days late for my period. I’ve had lots of pregnant symptoms but home pregnancy tests looked negative (I’ve taken 4). For the past 3 days I’ve been more crampy than usual, but no period. I got home from work tonight, felt my underwear get wet so I went to the bathroom thinking I had started my period. It was just lots of watery discharge with just the slightest amount of brown tinge to it. Just enough to notice when I wiped (wearing dark colored underwear so I didn’t see it in my panties). I never have brown discharge at the start of my period - at the end? Yes. But never at the beginning. I am so confused.